#Sunken Mandala (沈曼陀羅) — Vertical-Tier Mega-Dungeon

Contents

12–20-floor vertical dungeon. Screaming Hell + Shonetsu mixed. Deepest-floor great treasure: masterwork weapon + Hell Schools initiation 1× + Return Route Clue. 8–15 sessions.

Main Rulebook Cross-References

- Required: Yoma Bestiary Templates · Zone Gimmicks · Loot Table

- Reference: Underwater Environment Checks · Rank 10 Renown

- Within this supplement: Index · Hell Schools (Kyoukan · Shonetsu) · Spirit Realm Relics

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#§ Scent (香) — The Dungeon's Atmosphere

The Sunken Mandala has the peculiar structure of widening as you descend. Once you pass through the narrow cave entrance, a vertical shaft bored into the earth appears. This shaft spreads out like a giant mortar: with each floor you descend, the view grows more vast. But the water is always dark, and the distant walls are blanketed in faint mandala patterns. The colours are orange, black, blood-red, and the yellow glow of countless candles floating on the water's surface.

The air is breathable, but humid and heavy. Some floors are knee-deep in water; others rise to the waist or chest. Deeper floors bring fully submerged zones where the water covers your head. Yet even underwater, flame burns — oil fire, or hellfire. The paradox of water and fire coexisting simultaneously is the dungeon's foundation.

Mandala paintings cover every wall. At first they are complete, but as you descend the edges begin to break away, the centres fade, and finally the mandalas disappear. This loss of the mandala is the core of the dungeon's narrative. The players witness the collapse of the world's structure as they descend. Screaming Hell is "the hell of screams," but in this dungeon screams are inaudible — the water swallows every sound. Instead, vibrations reach the body: the feeling that somewhere in the distance someone is screaming.

In the deepest place, a great presence waits. At first it is felt only as a shadow. Somewhere below floor 12, the PCs begin to hallucinate a giant eye floating above their heads. That eye might be a Buddhist presence painted at the mandala's centre, or the lord of hell, or the bitter spirit of a previous Drifter. The GM leaves this interpretation open. Until the PCs come face to face with the deepest-floor boss, they do not know what they will be fighting.

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#§ Law (法) — Entry · Progression · Rewards

#Entry Conditions

1. Entry into Screaming Hell in Chapter 3 complete. At least Act 1 experienced. Must be familiar with the topographic features of Screaming Hell.
2. Map clue obtained. Hear the story of "Sunken Mandala" from a Chapter 3 NPC (pilgrim · guardian · hermit). The map itself is incomplete — it only shows the route to the entrance.
3. Means of underwater breathing. At least one of the following:

• Onmyoji talisman "Water (水) Breath Talisman" — 3 uses prepared.
• Shonetsu-ryu rank 1 or higher "Fire-Breath Technique" — allows breathing underwater.
• Specific relics: Sea-Diver's Amulet · Webbed Hand · Deep-Sea Breathing Bead (see Spirit Realm Relic Table).

1. Party consent. Players agree to allow departure from the main-story sessions.

#Recommended PC Rank

A Rank 10 Renown Title holder is a campaign-ending mechanism under the main rules. Renown declaration at the Mandala's deepest floor is permitted, but after the declaration the PC narratively retires from the campaign (following the main rulebook Rank 10 Renown principle).

#Estimated Sessions

Average progression per session: 1.5 floors. Floors with complex structure in the middle and late stages (floors 9–16) are 1 floor/1 session.

#Main Rewards

3 great rewards from the deepest floor:

1. 1 masterwork weapon — Bound to 1 member of the party. Chosen from the "masterwork" tier in Spirit Realm Relics.
2. Hell Schools initiation 1× — 1 type from Kyoukan-ryu or Shonetsu-ryu. The recipient automatically gains rank 1 in the school. Bound to 1 member of the party.
3. Return Route Clue — +3 bonus to the Chapter 5 Return Ending check. Shared by the party.

Incidental floor loot:

• Small loot per floor (rounds · silver · talismans · lower-grade relics).
• Mid-grade to high-grade relics hidden in some floors.
• Cumulative loot is equivalent to 2 masterworks on 16-floor completion.

#1-Time Principle for Great Rewards

Hell Schools initiation is strictly 1-time. Only 1 member of the party may receive it. Reattempting the dungeon does not allow re-receiving it. This preserves the narrative significance of this dungeon — the privilege of one who has reached the depths of the mandala.

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#§ Floor Structure: Detail

#Floor 1 — Entrance Cave (入口洞)

Theme: A narrow crack in a coastal cliff. Knee-deep water. Faint daylight filters in.

Overview: This floor is both the introduction and the last retreat. The PCs receive their first sensation of "entering another world" here. Atop the cliff sits a single pilgrim — the dungeon's warden.

Encounters:

• Warden Pilgrim (Rank 1 NPC). Does not give their name. Repeats "Below is a place you cannot return from" three times. No further conversation possible.
• Small oni-fish (鬼魚) 2–3 (Rank 3). Fish that bite ankles. Underwater movement check target 12; on failure, 1 Wounds.

Puzzle: Tide timing.

• The crack in the cliff rock opens every half-round. Outside the opening moment, the water is too strong to pass.
• When the warden says "now," enter. If they do not speak, wait 1 round.
• If the party misses the timing: 2 Wounds + swept back by the counter-current and must start again.

Treasure:

• "Lake Talisman" 1 given in goodwill by the warden. Underwater breath check +3 bonus, 1 time.
• "Oni-Fish Fang" 2 from the oni-fish bodies (worth 3 silver).

Danger: Water pressure mild. This floor can be cleared without injury.

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#Floor 2 — Gate of Water (水門)

Theme: A massive iron gate, half-submerged. 7 talismans arranged in a circle in front of the gate.

Overview: The gate is sealed. The talismans must be removed in the correct order. Each talisman bears a single line of a Buddhist sutra; removing them in the wrong order summons the gatekeeper wraith.

Encounters:

• Gatekeeper Wraith (Rank 5 yoma). Automatically summoned when the talisman order is wrong 2 or more times. Cannot be damaged by normal attacks — it only vanishes when all talismans are removed. Until then, it inflicts the Name Loss debuff on PCs (a state in which they forget their true name).

Puzzle: Talisman alignment.

• Read each talisman's single sutra line and estimate the correct order (the original sutra's sequence).
• Onmyoji- or monk-type PCs: Wisdom check target 12 on success = automatic success.
• On failure, proceed by guessing. For each 1 order error: summon the gatekeeper 1 time.
• Sample correct order (GM's discretion): Talisman 1 → 3 → 5 → 7 → 2 → 4 → 6.

Treasure:

• When the gate opens: "Sutra Box" 1. Contains "Protective Sutra Scroll" (equivalent to 3 talismans).
• "Water-Pressure Lantern" 1 hanging above the gate — carried on lower floors, grants underwater vision +3.

Danger:

• When the gatekeeper is repeatedly summoned, the Name Loss debuff on PCs persists until session end. PCs must speak of themselves only as "I" rather than using their name (roleplaying penalty).

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#Floor 3 — First Confession Chamber (初懺悔室)

Theme: Knee-deep water. Brazier fires blazing on all four walls. Paper lanterns drifting on the water.

Overview: This room is the space of the "confessing dead." Dozens of wraiths kneel in the water. They are whispering their sins — and hearing them causes the PC's own sins to surface.

Encounters:

• Confessing Dead 30 bodies (Rank 2 each). No hostile intent. However, when a confessing dead approaches a PC, the PC recalls their sins and must make a Mental Save target 13. On failure: 1 Wounds + Heart change.
• On a successful check, the dead withdraw, and the PC confronts the weight of their own sin — a roleplaying opportunity.

Puzzle: Confession choice.

• At the centre of the room is 1 "Bell of Confession."
• Ring it and all the dead disappear, allowing progress to the next floor.
• To pass without ringing it: all PCs must succeed on Mental Saves. Ringing makes progress easier, but the debt of "one who did not confess" lingers (additional dead summoned on later floors).

Treasure:

• PCs who confessed (succeeded on the check) receive "Bead of Confession" 1 from the dead. Heart change modifier +1 (1 time).
• "Sutra of Confession" scroll below the bell — used for deciphering inscriptions.

Danger:

• Heart changes affect the depth level (深度) in the main rulebook rules. See main rulebook Three Ways and Six Hearts.

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#Floor 4 — Mirror Corridor (鏡廊)

Theme: The walls on both sides of a narrow corridor are all water-mirrors. With every step you see another version of yourself.

Overview: The reflections in the mirrors mimic the PCs. But they gradually start to behave differently. At some moment the reflections burst out of the mirrors and attack the PCs.

Encounters:

• Self-Reflection Body — same number as PCs. An exact copy of each PC's stats (stats -2). Same Kata, same weapon. But the darker side of the main rulebook depth (心度) is emphasised.
• Killing the reflection gives that PC, as the experience of confronting their own dark side, +1 to rank progression checks (until session end).

Puzzle: Mirror reflection angle.

• At the corridor's end, 7 mirrors are arranged in a circle. Shine a light (1 fire lantern) at the exact angle to open a hidden door in the centre.
• Wisdom check target 14 on success = angle calculation success.
• On failure, the mirror shatters and an additional reflection is summoned from that mirror.

Treasure:

• "Mirror Shard" 1 (rare material). Can be used to craft reflection talismans.
• Behind the central door: "Silver Mirror Fan" 1 (mid-grade relic).

Danger:

• During combat with the reflection, PCs face their own Kata — Evasion check difficulty +2.
• If the reflection uses a Kata first, the PC's own Kata is sealed for 1 round.

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#Floor 5 — First Mandala Chamber (初曼陀羅室)

Theme: A circular room. A great mandala painting on the floor. The mandala is half-submerged in water. Pilgrim ghosts on the walls are praying.

Overview: This room is where the mandala first reveals its loss. Half of the floor mandala is submerged in the water, the pattern invisible. 6 pilgrim ghosts stand by the walls — they pray to restore the mandala.

Encounters:

• Pilgrim Ghosts 6 bodies (Rank 4 each). No hostile intent by default. Attack if their prayer is disturbed.
• Mandala Guardian 1 body (Rank 6). Seated at the mandala's centre. Attacks immediately if a PC desecrates the mandala (stepping on the pattern, etc.).

Puzzle: Mandala restoration.

• The submerged half of the mandala must be restored.
• Required knowledge: Buddhist mandala iconography. Wisdom check target 15 on success = grasp the restoration method.
• Restoration materials: "Mandala Fragment" 12, floating on the water's surface. Collected while reading the current.
• Collecting all fragments + placing each in the correct location completes the mandala. The guardian gives the PCs a blessing — recover 1 round upon entering the next floor.

Treasure:

• Mandala restoration success: "Mandala Guardian Talisman" 3 (each gives +2 to underwater breath).
• Guardian's blessing: +3 bonus to the first check on the next floor.
• Restoration failure (guardian defeated): "Damaged Mandala Fragment" — an ill omen on subsequent floors.

Danger:

• If the mandala is desecrated, all wall ghosts become hostile simultaneously (6 bodies attack at once — extreme danger).
• Leaving without restoring the mandala: "Mandala's Curse" on subsequent floors — check -1 (until leaving the dungeon).

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#Floor 6 — Hellfire Staircase (業火階)

Theme: A space with water up to the waist. In its centre, a staircase of flame burning above the water's surface. Below the stairs is underwater; above the stairs is flame.

Overview: The descent route is the Hellfire Staircase. On this floor, for the first time, water and fire explicitly coexist. Walk the stairs and suffer Burns; attempt to avoid by diving underwater and risk drowning + the flame-body soldiers below.

Encounters:

• Flame-Body Soldiers 5 bodies (Rank 5 each). Move underwater, but the tips of their spears carry flame. Deals physical damage + Burn damage simultaneously.
• Combat on the stairs is impossible (space is too narrow). Engage underwater below the stairs.

Puzzle: Severing the flame.

• The flame's source on the staircase is 3 oil pipes above the water surface. Block all oil pipes and the staircase cools.
• The oil pipes are 3m above the water surface. Leap check target 12 required. On failure: 1 Wounds.
• To block the oil: "a handful of earth" or "fire talisman." Without either: block by hand (2 Wounds Burn).

Treasure:

• Severing the flame success: "Hellfire Ash" a handful (Shonetsu-ryu training material).
• 1 of the flame-body soldiers' spears — "Hellfire Spear (業槍)" (mid-grade weapon).
• "Oil Lantern" 1 hidden midway up the stairs — maintains underwater vision for 6 rounds.

Danger:

• Underwater + fire mixed gimmick: Burn damage is valid even underwater. Receiving Burn damage while submerged makes the recovery check difficulty +3.
• Moving on the stairs: 1 Wounds Burn per short stretch. Full traversal is typically 3 Wounds.

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#Floor 7 — Second Mandala Chamber (第二曼陀羅室)

Theme: A circular room. The mandala's four corners have disappeared. The centre is intact, but the boundary has worn away.

Overview: The mandala's loss progresses. This floor's mandala has its centre intact but no boundary ward. Without the boundary ward, yoma flow in from outside and drift around the room.

Encounters:

• Mandala Guardian 1 body (Rank 7). This guardian is weaker than the previous floor; its defense is at -3. Without the boundary ward its power is scattered.
• Drifting Yoma 4 bodies (Rank 4 each). Existences that flowed in from beyond the boundary ward. Aggressive.

Puzzle: Restoring the boundary ward's corners.

• All 4 corners must be restored. Each corner requires something different:
• Northwest: "Mandala Guardian Talisman" (Floor 5 reward)
• Northeast: "Bead of Confession" (Floor 3 reward)
• Southwest: "Sutra Scroll" (Floor 2 reward)
• Southeast: a drop of blood from one PC (consume 1 Wounds)
• When all 4 corners are restored, the guardian is reinforced again (original Defense +5). Thereafter the guardian in this room becomes an ally (at GM's discretion, provides support on later floors).

Treasure:

• Corner restoration success: "Mandala Ward Stone" 1 (rare relic).
• Guardian alliance: support 1 time at an unspecified point on the next 1–2 floors (substitutes for 1 check).
• Drifting Yoma defeated: 1 core per yoma.

Danger:

• If corner restoration fails, the guardian self-destructs (shatters the mandala's centre). From that point on, all mandalas on subsequent floors are permanently in a damaged state.

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#Floor 8 — Stone Boat (石舟)

Theme: A great circular cavity. In the centre, giant stone pillars stand erect. 3 "boats" made of stone resting atop the pillars. Water below.

Overview: This floor's structure is vertical. You must cross between the stone boats atop the pillars to reach the descending stairway. The distance between pillars is great, and Screaming Hell yoma are swimming in the water below.

Encounters:

• Screaming Hell Yoma 1 body (Rank 8, Tier 1). Exists only in the water. Immediately targets a PC who falls.
• The Screaming Hell Yoma attacks with scream waves. Perception check target 15 required within its radius. On failure: 1 Wounds + stunned for 1 round.
• The Screaming Hell Yoma cannot climb the pillars — it cannot reach the stone boats.

Puzzle: Crossing the stone pillars.

• 3 pillars, 3 stone boats. Push a boat until it rests against another pillar to make a bridge.
• Pushing a boat requires a Physique check target 14. Cooperation by 2 people: +3.
• On push failure, the boat falls into the water. The boat cannot be retrieved.
• At least 2 of the 3 boats must be successfully bridged for a safe crossing. If 1 or fewer, a leap check is needed (on failure, fall into the water).

Treasure:

• "Stone Pillow (石枕)" 1 hidden below a stone boat (Hell Schools training material).
• Screaming Hell Yoma defeated: "Scream Crystal" 1 (rare relic; usable by those with Kyoukan-ryu rank 1).

Danger:

• On falling into the water: immediate Screaming Hell Yoma attack. Death in 2 rounds if not rescued.
• Rescue requires a collaborative Physique check of 16 or higher by 2 people.

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#Floor 9 — Silent Bath (沈默浴)

Theme: A floor shaped like a great bathtub. Hot water (Burn damage) filled to chest height. Dozens of coffins submerged within.

Overview: The coffins contain the remains of previous Drifters, pilgrims, and nameless dead. Open the one correct coffin to find the key to the descending stairway. Open the wrong one and the wraith inside wakes.

Encounters:

• Coffin Wraiths up to 5 bodies can be summoned (1 body per wrongly opened coffin). Rank 6 each. Aggressive.
• 1 specific coffin contains the ghost of a previous Drifter — when opened, brief conversation is possible (GM provides 1 fragment of the previous Drifter's records).

Puzzle: Choosing the true coffin.

• 12 coffins. Each coffin has a name written on it (faded, requiring decipherment).
• One of the names is "the name of a previous Drifter mentioned in Chapter 3" — based on the clue provided by a Chapter 3 NPC.
• Name decipherment check target 13.
• Correct coffin: the coffin bearing the previous Drifter's name. Inside it: the descending key + the previous Drifter's last words (narrative reward).

Treasure:

• Correct coffin: descending key 1 + previous Drifter's last words (Return Clue fragment 1).
• Side coffins: small loot per coffin (silver · talismans · weapon fragments).
• Conversation with the previous Drifter's ghost: 1 warning about a floor below.

Danger:

• Burn damage: 1 Wounds per round. Accumulates the longer you stay.
• When many wraiths are summoned: up to 5 bodies fighting simultaneously. A Rank 8 party can barely push through.

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#Floor 10 — Third Mandala Chamber (第三曼陀羅室)

Theme: The mandala is half-collapsed. Only the centre barely holds; the rest has sunk into the water like shattered tiles.

Overview: This room is the point where the mandala's loss accelerates. A collapse cascade is already in progress — the moment the players arrive, more room tiles are falling.

Encounters:

• Collapse Yoma 3 bodies (Rank 6 each). Grow stronger as the mandala breaks apart. When the mandala fully collapses, additional yoma are summoned (up to 5 more).
• Emotional Wave — the mandala's "scream" echoes throughout the room. A Mental Save target 13 is required every round. On failure: 1 Wounds.

Puzzle: Stopping the collapse cascade.

• 5 still-connected mandala tiles must be secured.
• A Finesse check target 14 is required for each tile.
• All 5 tiles secured successfully: collapse stopped, mandala maintained (partial restoration is not possible).
• On failure: that tile collapses + Emotional Wave difficulty +2.

Treasure:

• Collapse stopped successfully: "Mandala Fragment" 3 (rare material).
• Yoma defeated: each yoma's core + incidental loot.
• "Bell of Silence" hidden in the room's centre — neutralises scream waves 1 time.

Danger:

• This floor has a time limit. Securing checks must be completed within 7 rounds. If exceeded, the mandala fully collapses + 5 additional yoma summoned.

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#Floor 11 — Bell of Karma (業鐘)

Theme: A great underwater bell hanging at the centre. A dead person is trapped inside the bell.

Overview: On this floor, you must ring the bell to proceed to the next floor. But ringing the bell wakes the trapped dead. The bell must be rung 3 times, and the weight of the dead must be borne through the process.

Encounters:

• Dead Inside the Bell 1 body (Rank 8). Wakes each time the bell is rung. Fully wakes on the 3rd ring (combat).
• The woken dead are an avatar of a previous Drifter — the GM describes them as an emissary of Screaming Hell's lord.

Puzzle: Ring the bell 3 times.

• The bell hammer is submerged. Underwater search check target 12.
• To strike the bell, you must rise above the water surface. But a water-pressure wall surrounds the bell, making approach difficult.
• Each 1 ring requires: Physique check 13 or higher + 1 Wounds from water pressure.
• Completing 3 rings fully releases the dead inside the bell. Simultaneously, the descending stairway opens.

Treasure:

• "Karma Talisman (業の符)" 3 hanging above the bell (each gives Heart stability +2).
• When the dead are defeated: "Relic of a Previous Drifter" 1 (narrative reward, Return Clue fragment 1).

Danger:

• The water-pressure wall strengthens while ringing the bell. Water pressure damage accumulates with each strike.
• The released dead are equivalent to Rank 8 in combat. A Rank 9 party can push through.

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#Floor 12 — Fourth Mandala Chamber (第四曼陀羅室)

Theme: The mandala is completely lost. The room is an empty circle. Even the wall patterns have disappeared. Only water remains.

Overview: This floor is the short-completion deepest floor (when completing the dungeon at floor 12). The GM can conclude the campaign at this point. In the space where the mandala has completely vanished, its remnant avatar appears.

Encounters:

• Mandala Remnant Avatar 1 body (Rank 9, mid-grade boss). A being in which the mandala's memory has taken physical form. Combat + narrative dialogue.
• Conversation possible — ask the avatar "why did the mandala disappear" to receive 1 fragment of a clue about the true nature of Avici.
• Combat is optional. Peaceful resolution on successful Negotiation.

Puzzle: Mandala re-creation.

• Combine the mandala fragments obtained from previous floors.
• Fragments needed: at least 5 (obtained from floors 5 · 7 · 10 · 11).
• Re-creation check target 16.
• On success: a new mandala appears in the room. From this point on, all subsequent floors proceed with the mandala in a partially restored state.

Treasure:

• Short-completion great reward (up to floor 12): Hell Schools initiation 1× + masterwork weapon 1 + Return Clue fragment 1.
• Mid-grade boss defeated: "Remnant Crystal" 1 (material for a Divine Treasure-grade relic).
• Mandala re-creation success: "New Mandala Talisman" 3 (each gives +1 to all checks, 1 time).

Danger:

• During combat with the remnant avatar: 2 phases. After the first phase is defeated, the mandala's remnant is reabsorbed and the 2nd phase (equivalent to Rank 11) appears.
• When Negotiation fails, combat begins immediately.

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#Floor 13 — Crossing the Boiling River (沸川渡)

Theme: A horizontal-relocation floor. A boiling river flows. A ferryman yoma presents the crossing conditions.

Overview: Not a descent but horizontal relocation. This floor is the passage for completing all 20 floors. A single river must be crossed, and the river is close to hot lava.

Encounters:

• Ferryman Yoma 1 body (Rank 7). Neutral. Demands payment for the crossing — "one fragment of memory" or "one fragment of a name."
• Pay the price and cross safely. Refuse and the PCs must cross the river themselves (Burns + encounter with flame-body soldiers).

Puzzle: Paying the ferry fare.

• The ferryman's demands:
• "Offer me one of your most precious past memories" — accept and lose 1 memory (roleplaying penalty; -3 to checks related to that memory).
• Or "Offer me your true name" — accept and lose your name (similar to the gatekeeper debuff from the earlier floor).
• Neither is easy to accept. The PCs must agonise.

Treasure:

• Crossing completed: "Immovable Stone Tablet (不変の石板)" 1 (rare relic, Burn resistance +5).
• Refusing payment + successfully crossing the river on your own: "Flame of Courage (勇気の炎)" 1 (narrative reward).

Danger:

• Crossing the river directly: 2 Wounds Burn per round. Average 3–4 rounds required. Burn accumulation is severe.
• 6 flame-body soldiers encountered on the water surface. Engage while moving.

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#Floor 14 — Ruins of the Archive (文書庫)

Theme: A collapsed archive. Records of previous Drifters piled on bookshelves submerged in water.

Overview: This floor is a narrative-focused floor. Information gathering over combat. Investigate the scrolls and books containing the records of previous Drifters.

Encounters:

• Dead Inside the Records many (Rank 3 each). Small wraiths summoned when records are touched. Non-combat resolution possible — not summoned if records are handled with respect.
• Archive Custodian 1 body (Rank 7). The wraith of one of the previous Drifters. Conversable. Answers questions — but demands "1 fragment of memory" for each question.

Puzzle: Decoding the records.

• The records are encrypted. Decoding checks reveal information step by step.
• Multi-stage decoding:
• Stage 1 (10 or higher): Identify the names of previous Drifters.
• Stage 2 (13 or higher): Clue to the location of the Sealing Stone.
• Stage 3 (16 or higher): Core fragment of the Return Route (+3 bonus to Chapter 5 Return Ending).
• All 3 stages successful: major clue secured.

Treasure:

• "Journal of a Previous Drifter" 3 volumes (rare relics, narrative reward).
• Archive Custodian's cooperation: advance disclosure of the gimmick for 1 floor below.
• Stage 3 decoding success: core Return Route clue.

Danger:

• When records are damaged: a mass of dead summoned (12 bodies). No option but to flee.
• Accumulation of the Custodian's "memory fragment" demands: if you comply 3 or more times, the PC enters a memory gap state (narrative penalty).

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#Floor 15 — Fifth Mandala Chamber (第五曼陀羅室)

Theme: A mandala devouring another mandala. Two mandalas overlap, one engulfing the other.

Overview: This floor is the extreme form of the mandala's loss. One mandala is consuming another. The consuming mandala has transformed into a giant yoma, and the consumed mandala howls within it.

Encounters:

• Mixed-Mandala Yoma 1 body (Rank 9, mid-grade boss). A being in which 2 mandalas have fused. Has two consciousnesses — an aggressive consciousness + a rescue-request consciousness.
• Can engage the aggressive consciousness in combat. However, responding to the rescue-request consciousness avoids combat + allows performance of the separation ritual.

Puzzle: Separation ritual.

• The two mandalas must be separated.
• Required materials: Mandala talismans · fragments · remnant crystals obtained from floors 7 · 10 · 12.
• Separation ritual check target 17.
• On success: the two mandalas separated + yoma vanishes (without taking damage).
• On failure: transitions to combat.

Treasure:

• Separation success: "Double-Mandala Talisman" 1 (very rare; +2 to all checks, 1 time per session).
• Combat victory: yoma core + "Mixed Crystal" (Divine Treasure-grade relic material).
• Responding to the rescue request: narrative reward + obtain the "name" of the consumed mandala (true-name knowledge, useful for defeating specific yoma).

Danger:

• In combat, the aggressive consciousness is reinforced (stats +2). Even a Rank 9 party is in danger.
• Separation ritual failure + retry: some materials lost.

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#Floor 16 — Shadow of the Great Presence (巨影)

Theme: A great shadow hangs down from the ceiling. This shadow is a harbinger of the great presence on the deepest floor.

Overview: On this floor, for the first time, the players confront the great presence on the deepest floor indirectly. Only its shadow is visible — eyes, tentacles, enormous scale. But the body itself has not appeared yet.

Encounters:

• Shadow Yoma 1 body (equivalent to Rank 10, Lord-grade phase 1). An avatar of the final boss. Only phase 1 of 2 is fought on this floor.
• Mid-combat, the shadow yoma says "it is not yet time" and withdraws when phase 1 Wounds are depleted.
• The shadow's words: "Why have you come this far? Turn back. Or you will come to know my name."

Puzzle: Evading the shadow.

• To evade the shadow instead of fighting: need to use the "Bell of Silence" (Floor 10 reward).
• Evasion success: quietly descend to the next floor — but on the deepest floor, the shadow yoma appears in complete form (boss stats +5).
• In combat: defeat phase 1 to face only a weakened phase 2 on the deepest floor.

Treasure:

• Shadow Yoma phase 1 defeated: "Shadow Fragment (影の欠片)" 1 (Divine Treasure-grade relic material).
• "Descending Key" 1 at the room's centre — unlocks the next floor.
• Evasion success: shortcut to the deepest floor (floors 17–19 can be skipped, but boss is strengthened).

Danger:

• The Shadow Yoma's attacks are primarily mental damage. On Mental Save failure, the PC enters a "Fear" state — cannot act for 1 round.
• Phase 2 is truly frightening. A moment's inattention and the entire party is wiped.

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#Floors 17–19 — GM Expansion Floors (Optional)

Theme: GM's discretion. Design freely to fit the campaign.

Suggested structure:

• Floor 17: Re-experiencing elements of earlier floors in reverse — mirrors, mandalas, and the Hellfire Staircase mixed together in no order. Total loss of direction.
• Floor 18: A vast cavity. Ceiling · floor · walls are all mandala. Gravity direction is arbitrary. No knowing which way is "down."
• Floor 19: The silent floor. Absolutely no sound. All checks proceed by sight alone. Perception checks auto-fail.

Encounters · Puzzles: GM's discretion. Basic principles:

• Per floor: Lord-grade 1–2 bodies + mid-level small group 1–2.
• Puzzle difficulty: 15–17 or higher.
• Treasure: high-grade to rare.

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#Floor 20 / Deepest Floor — Sealed Core of the Mandala (封印曼陀羅核)

Theme: A vast circular cavity. At the centre, the mandala's core emitting light. The final boss upon it.

Overview: The origin of all mandalas. Here the mandala is completely restored — this is the original from which all mandalas come. But there is a final boss guarding the core.

Boss Combat: See § Boss.

After Boss Defeated:

• The mandala's core becomes accessible. On approach, 3 types of great rewards are unlocked.
• Receiving the great rewards:
• Choose 1 masterwork weapon (from the "masterwork" tier in Spirit Realm Relics).
• Hell Schools initiation (Kyoukan-ryu or Shonetsu-ryu). Bound to 1 PC. That PC automatically gains rank 1 in the school.
• Return Route Clue (+3 bonus to Chapter 5 Return Ending check).

Narrative After Boss Defeated:

• At the mandala's core the PCs catch a fleeting glimpse of the structure of the world. The GM stages this scene in silence — no dialogue, only images.
• All PCs are given the title "One Who Has Seen the Mandala." Wisdom check +1 at all times in subsequent campaigns.

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#§ Boss — Lord of the Sunken Mandala

#Overview

Name: Chinman Yatenno (沈曼夜天王) (provisional; GM's choice)

Type: Lord-grade yoma, 2 phases.

Rank: Equivalent to Rank 11.

Motif: The central being of a Buddhist mandala in corrupted form. Originally a mandala guardian, it has absorbed the qualities of hell through long years of submersion.

#Canon Operation Principles

This boss is operated solely by the main rulebook combat system. Do not use separate HP values, armour class, or dice damage.

Mandala cores are treated as minion-grade structures. Each core has Wounds 1 / Defense 15; when destroyed, it cancels 1 of the boss's bonus effects in that round.

#Phase 1 Patterns

Mandala Spread

• Spreads a pattern across the whole room. PCs in the same zone: Evasion check target 14. On failure: 1 Wounds + bound on the pattern, movement cost +1.
• While the pattern remains, friendly yoma in the same zone gain Defense +1.

Core Summon

• At the end of every round, if 2 or fewer cores remain, replenish 1 core.
• Destroying cores first negates the next round's Core Discharge or Name-Giving 1 time.

#Phase 2 Patterns

Transition condition: Phase 1 Wounds reach 0.

Transition staging: The boss collapses and the "mandala core" embedded within is revealed. Light surges from the core and reconstructs the boss's body.

Core Discharge

• All in the same zone: Mental Save target 16. On failure: 2 Wounds + 1 Heart wavering roll.
• If 2 or more cores remain, add a forced movement of 1 space after the discharge.

Mandala Reconstruction

• Declare 1 zone around the boss as a boundary. PCs ending their turn inside that boundary take 1 Wounds.
• Using a Mirror-Shard-type relic neutralises the boundary damage in that round.

Name-Giving

• Designates 1 PC. Target makes a Mental Save target 18.
• On failure: cannot act until the next lull. A friendly in the same zone can spend 1 action to tear the pattern, or destroying 1 mandala core within the round removes the effect.

#How to Defeat the Boss

1. Head-on: Defeat 2 phases. Long battle of 5–7 rounds for a Rank 9–10 party.
2. True-Name Invocation: If the true name is obtained from "Records of Previous Drifters" (Floor 14 reward), at the start of phase 2 Defense -2 and 2 cores removed.
3. School Affinity: When a Kyoukan-ryu or Shonetsu-ryu PC is present, can negate boundary damage 1 time, or turn the boss's Heart wavering roll against it.
4. Dialogue Resolution: Performing the rescue-request ritual allows peaceful resolution even if Wounds are not at 0. In this case, all great rewards are obtained.

#Boss Dialogue (Optional)

• (Phase 1 opening) "You have reached the depths of the mandala. Here your mandala too will be submerged."
• (Phase 1 mid) "There was a time when I was called a guardian. Now it is forgotten."
• (Phase 2 transition) "Look deeper. At what you truly are."
• (Phase 2 resolution) "Ah. Forgive... me..."

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#Deepest-Floor Great Rewards (Guaranteed, Conditional on Boss Defeat)

1-person Bound principle: The weapon recipient and the school initiation recipient must be different PCs. Duplicate receipt by the same PC is prohibited — this is to maintain narrative balance.

#Floor-by-Floor Incidental Loot Summary

#Narrative Rewards (Party Shared)

• Title "One Who Has Seen the Mandala": Wisdom check +1 at all times.
• 3 journals of previous Drifters: Used in Chapter 5 ending roleplay.
• Return Route Clue 3 fragments (floors 9 · 11 · 14): Securing all clues accumulates +3 bonus to the Return Ending check.
• True-name knowledge: +3 bonus against specific Lord-grade yoma (used in subsequent main-story encounters).

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#§ Pacing Guide

#Progression Speed per Session

Average 1.5 floors per session. Complex floors (5 · 10 · 14) are 1 floor/1 session.

#Pacing Advice

Do not rush. The appeal of the Sunken Mandala is the weight of the descent. Let the PCs feel that the deeper they go, the harder it is to turn back. On each floor:

1. Entry staging: Describe the descending scene with silence. The depth of the water, the colour of the flame, the state of the mandala — in sentences.
2. Encounter introduction: Don't let enemies appear suddenly. Start with a silhouette from a distance.
3. Puzzle pacing: Give the players time to think. Be sparing with hints, but when necessary provide them through an NPC (Archive Custodian · guardian).
4. Loot distribution: Rather than distributing all loot at session end, describe it immediately upon acquisition.
5. Session conclusion: End at a floor's conclusion. Avoid ending mid-floor (difficult to resume).

#Emphasising Narrative Weight

The mandala's loss is not a mere gimmick. As the PCs descend:

• The sensation that their own mandala (self) is also being lost. Actively encourage Heart changes.
• The discovery that previous Drifters also walked this path. Yet they did not return.
• Questions about structure: Why is the mandala disappearing? Who erased it? — Indirect answer on the deepest floor.

The GM should pose emotional questions to the PCs on each floor:

• Floor 3: "What is the heaviest of your sins?"
• Floor 5: "What is your mandala (the centre of your life)?"
• Floor 9: "Who might be in this coffin? Is it someone you know?"
• Floor 12: "The mandala has completely disappeared. How do you feel?"

Roleplay responses are reflected in situational bonuses (+1 to +3, GM's discretion).

#Difficulty Adjustment

When the party is too strong:

• Encounters per floor +1.
• Boss Wounds +2 or mandala cores +1.
• Puzzle check difficulty +1 to +2.

When the party is too weak:

• Encounters -1.
• Mandala Guardian's blessing triggers automatically.
• Previous Drifter ghost's advice 1 additional time.
• All PCs recover 2 Energy or 1 Wounds at phase transition.

#Session Resumption Preparation

When resuming after a long break, the GM:

1. Prepares a session resumption card: current floor, party Wounds · Energy state, rounds, loot acquired, puzzles in progress.
2. Provides a previous session summary: within 3 paragraphs.
3. Rebuilds the atmosphere: the first scene of resumption begins with a description of the current floor. Environment over encounters.
4. Reconnects with players: the first 10 minutes are for restarting RP. No rushing immediately into combat.

#Suspension Handling

When a PC leaves mid-descent:

1. State the exit cost explicitly: 2 Wounds from water pressure + 2 rounds.
2. Psychological debt: "Record of the Deep" — nightmare check -2 until re-entry.
3. Not from the beginning on re-entry: resume from the same floor. But already-looted items are not restored.
4. When leaving from below floor 12: special penalty — in subsequent main-story sessions, the "mandala beckons" event occurs (staged at GM's discretion).

#Relationship with Rank 10 Renown Declaration

A PC may declare Rank 10 Renown during the deepest-floor boss combat. However:

• The Renown user narratively retires after this session.
• Of the 3 types of great reward, 1 type (masterwork weapon) may be left as a keepsake of the Renown user.
• The school initiation cannot be Bound to the Renown user (meaningless after retirement).
• The Renown user's retirement scene can be staged as fusion with the mandala core — highly narrative.

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#§ Environment Gimmick Detail

#Underwater + Fire Mixed Gimmick

The dungeon's core gimmick is the simultaneous existence of water and fire. Apply the underwater and Burn effects from the main rulebook Zone Gimmicks in overlap.

#Water Pressure Accumulation

• Water pressure grade per floor: Grade 1 on Floor 1 → Grade 20 on Floor 20.
• 1 Wounds accumulates per round equal to the water pressure grade (can be reduced with water-pressure-defense talismans and relics).
• Water pressure defense means:
• "Lake Talisman" (Floor 1) — complete immunity for 3 rounds.
• "Water-Pressure Lantern" (Floor 2) — water pressure -3 while carried.
• "Immovable Stone Tablet" (Floor 13) — permanent water pressure -5.
• Shonetsu-ryu rank 1 or higher — water pressure -3 at all times.
• When water pressure accumulation exceeds 15: Barotrauma state — Mental Save -3, attack check -2.

#Burn Accumulation

• Burn damage accumulates on specific floors (floors 6 · 9 · 13 · 15).
• Burn stages: mild (1 Wounds per round) → moderate (2 Wounds per round) → severe (5 Wounds per round, movement -1).
• Burn treatment:
• Staying in water (non-hot) — 1 round reduces by 1 stage.
• "Healing Talisman" — immediate reduction by 1 stage.
• "Flame of Courage" (Floor 13) — Burn immunity for 5 rounds.
• Underwater + Burn overlap special rule: receiving Burn damage inside hot water makes the recovery check difficulty +3.

#Breath Check

• On entering a fully submerged zone (floors 8 · 11 · 16 · 20), a breath check is required every round.
• Base check: Physique check target 12.
• On failure: 1 Wounds + next round's check difficulty +1.
• 3 consecutive failures: unconscious.
• Breath means:
• Onmyoji talisman "Water Breath Talisman" — exempt for 10 rounds per 1 use.
• Shonetsu-ryu "Fire-Breath Technique" — unlimited breath underwater (requires rank 1 or higher).
• "Sea-Diver's Amulet" (Spirit Realm relic) — exempt from all underwater breath checks.

#Heart Tracking

Heart change possibilities per floor:

Follow the main rulebook Three Ways and Six Hearts. Heart depth changes after dungeon completion affect the Return Ending.

#Time (Round) Passage

This dungeon requires a long time. Average rounds per floor:

Cumulative rounds for 16-floor completion: approximately 85. 20-floor completion: approximately 110.

Round recovery:

• At safe points (refuges between floors): recover 2 rounds.
• Through Mandala Blessing (floors 5 · 7 · 12): recover 1 each.
• With specific relics (e.g. "Bell of Silence"): recover 1, 1 time.

When rounds are depleted, PCs enter a Fatigue state — all checks -1, cannot recover (until reaching a safe point).

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#§ Records of Previous Drifters — Narrative Supplement

#The Stories of Previous Drifters

"Records of Previous Drifters" collectable inside the dungeon: 3 volumes. Each record contains the stories of 3 previous Drifters. These records are used in Chapter 5 Return Ending roleplay.

#Record 1 — "The Fire Merchant"

Found at: Floor 14, Stage 1 decoding.

Summary: A merchant from 100 years ago. Adrift in Shonetsu Hell, he reached as far as the entrance to Sunken Mandala, but was consumed by the Screaming Hell Yoma on floor 8. His bones lie beneath a stone boat on floor 8.

Content:

"I, Kyuemon, merchant of Ibuse. I leave this record. If you are reading this, it means you too are here.

The mandala is vast. More than you believe. It is not a mere painting — it is the world itself. For the mandala to disappear is for the world to disappear.

I went deep. To floor 8. And there the Screaming Hell Yoma stole my name. One from whom a name is stolen cannot return even in death.

Protect your names. No matter what."

Narrative reward: PCs' understanding of the Name Loss debuff increases. +1 bonus to subsequent Name Loss checks.

#Record 2 — "The Blind Warrior"

Found at: Floor 14, Stage 2 decoding.

Summary: A warrior from 50 years ago. Lost his eyes in battle and went adrift. Reached as far as floor 16 of Sunken Mandala. Mentally and physically subsumed by the Shadow Yoma; gave up on returning.

Content:

"I, Isuke of the Yorisadaka clan. I can no longer see. No — from the beginning I could not see. I was blind.

But this place is visible to me. Because here, eyes are not needed. The mandala can be heard with the ears — through its vibrations.

I descended deep. To floor 16. Here I met the great shadow. The shadow gave me a name. I accepted that name.

Now I am part of the shadow. If you want to go further, do not call the shadow's name. If you call it, you too will become part of it.

But — to pass through the shadow, ring the Bell of Silence. The bell stops up the shadow's ears."

Narrative reward: Hint for clearing floor 16 (using the Bell of Silence). + Learn "the name of the previous Drifter" — automatic success on the correct-coffin check on floor 9.

#Record 3 — "The Nameless Monk"

Found at: Floor 14, Stage 3 decoding.

Summary: Era unknown. A monk whose name has been erased. Reached the deepest floor of Sunken Mandala. But successfully returned. Recorded the Return Route in their records.

Content:

"I abandoned my name. Who I once was does not matter. What matters is that I returned.

At the mandala's core I witnessed the structure of the world. The mandala is not a map of the world. The mandala is the spell that creates the world.

The lord tried to absorb me. I refused. There was one way to refuse — it was to abandon my name. With no name, there is nothing to be absorbed.

The Return Route is a narrow gap behind the mandala's core. To pass through that gap, four things are needed:

One: defeat the mandala's core or pass by it through Negotiation.

Two: know the name of one among the previous Drifters.

Three: one among you must accept a Hell School.

Four: all of you must be together.

With these four, you can return. If even one is missing, you too remain here."

Narrative reward: Unlock +3 bonus to Chapter 5 Return Ending check. 4 Return conditions disclosed.

#The Warden's Memory

The Warden Pilgrim of the entrance floor (floor 1) is actually 1 of the previous Drifters (GM's discretion — can be connected to 1 of the 3 above). Does not respond to conversation, but after the party has secured all records from floor 14, on returning they can face them again — a narrative afterglow.

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#§ Yoma Detail — Floor-by-Floor Yoma Operation Cards

This section is a GM summary to be directly transcribed into the main combat system. Organised using only Mob/Minion/Veteran/Elite/Lord, Wounds, Defense, gimmick, and resolution condition — no separate HP values or armour class.

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• [ ] Water pressure accumulation
• [ ] Heart change
• [ ] Owned loot (from previous floors)
• [ ] Special states (Name Loss · Mandala Curse etc.)

#Floor-by-Floor Quick Difficulty Adjustment

When the party is weak:

When the party is strong:

#Session Operation Timer

Based on a 3-hour session:

• 0:00–0:15 — Session opening, resumption prep
• 0:15–0:45 — Enter current floor, Encounter 1
• 0:45–1:30 — Puzzle or main combat
• 1:30–1:45 — Rest
• 1:45–2:15 — Conclude floor, acquire loot
• 2:15–2:45 — Introduce next floor (or conclude session)
• 2:45–3:00 — Wrap up session, record resumption point

1–2 hours allocated per floor. Complex floors are 1 floor/1 session; simple floors are 2 floors/1 session.

#Managing Player Fatigue

Mega-dungeon long-haul fatigue is dangerous. The GM should:

1. Alternate main-story sessions: After 2–3 sessions of Sunken Mandala, recommend 1 main-story session. Avoid 5 consecutive sessions in the same dungeon.
2. Atmosphere shift: Place at least one "bright moment" within each session. Loot discovery · NPC reunion · humour scene, etc.
3. Rest floors: Floors 5 and 12 are intentionally in a mandala-intact state — sections that provide a sense of stability. Recommended to end sessions here.
4. Listen to player feedback: After each session, ask "Is the mandala fun right now?" If the response is lukewarm, switch to the short form.

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#§ FAQ — Frequently Asked GM Questions

Q1. A PC is trying to deliberately desecrate the mandala. What should I do?

A. The Mandala Guardian immediately becomes hostile. After the party is defeated and the mandala collapses, it is permanently applied from that floor onward — all mandalas on subsequent floors enter a damaged state. This accumulates a -3 penalty to the Return Ending check.

Narratively, interpret this as the PC being afraid of or angered by the mandala. The GM stages this motivation in consultation with the PC.

Q2. What if a PC loses all means of breathing in a fully submerged zone?

A. Recovery of means is needed within 3 rounds. Otherwise unconscious → 1 Wounds lost per round from 1 round later → death in 5 rounds. Rescue is possible.

Rescue methods:

• Another PC shares a means of breathing (talismans etc.).
• Emergency ascent — return to the previous floor at a cost of 3 rounds.

Q3. When multiple PCs want the Hell Schools initiation?

A. 1-time principle. The party agrees to select 1 person. On failure to agree:

1. Simple vote (external player mediation possible).
2. The GM stages it as "the mandala's choice" — the mandala responds to one PC (e.g. connected to that PC's past background).
3. Compromise: other PCs receive priority on the masterwork weapon instead.

Q4. When is the timing for a Rank 10 Renown declaration?

A. Only possible during the deepest-floor boss combat. Declarations on floors 1–16 are prohibited — because it is not the narrative climax.

The Renown user cannot receive the great rewards (that PC retires). However, the masterwork weapon can be left as a keepsake — inherited by the next PC.

Q5. When running the main story and Mandala in parallel during the campaign, what is the order?

A. Recommended placement:

• Chapter 3 Acts 1–2 → Mandala floors 1–4 (after 2–3 main-story sessions)
• Chapter 3 Act 3 → Mandala floors 5–8
• Chapter 4 Acts 1–2 → Mandala floors 9–12
• Chapter 4 Acts 3–4 → Mandala floors 13–16
• Chapter 5 Act 1 → Mandala floors 17–20 (point at which Renown declaration is possible)
• Chapter 5 Acts 2–4 → Focus on main story ending, utilise Mandala full-run loot

Be careful not to have the main story conclude before Mandala full-run is complete.

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#Related Documents in This Supplement

• Index — Comparison of 2 mega-dungeons.
• Hundred-Doors Shrine — Another mega-dungeon that can be run in parallel.
• Hell Schools Index — Kyoukan-ryu · Shonetsu-ryu detail.
• Spirit Realm Relics — Masterwork · Divine Treasure-grade relic list.
• Premise — World-building basics.

#Main Rulebook Cross-References

• Yoma Bestiary Templates — Benchmark for boss and yoma stats.
• Zone Gimmicks — Underwater, Burn, water pressure environmental effects.
• Loot Table — Distribution rules.
• Rank 10 Renown — Renown declaration principle.
• Three Ways and Six Hearts — The relationship between Heart and mandala.

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Sunken Mandala — end.