#OSR Conversion (OSR Data Conversion)

Guidelines for converting B/X, OSE, and other OSR data into the Konsei Reiyotan system.

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#Basic Conversion Rules

#Dice System

#AC (Defense)

Use OSR ascending AC(AAC) as-is.

#HD → Wounds

#Attack Bonus

Convert OSR THAC0/attack bonus into a Konsei Reiyotan Courage modifier.

#Saving Throws

OSR Save → 2d10 + relevant ability >= 11 (baseline). Special abilities from high-level monsters should use targets of 13~15.

#Special Ability Conversion Guide

A 4-step procedure for turning OSR special abilities such as "Dragon Fear", "Paralyzing Gaze", and "Breath Weapon" into Konsei Reiyotan techniques:

1. Classify the technique type: Decide which maneuver type the ability belongs to.

• Persistent effect (Fear Aura, Regeneration) → [aptitude]
• One-shot heavy attack (Breath, Gaze, Charm) → [Kata] or [Attack B]
• Zone effect (Aura of Sleep, Web) → [stance] (maintained)
• Summon → [Kata] (0 Energy [Kata] maneuver, subject to the 2-times-per-round limit)

1. Set the Energy cost: Based on the original OSR use frequency.

• Always active → 0 Energy [aptitude]
• N times per day → "1/combat" or "N/round" limit
• 1/combat Critical Hit grade → 4~6 Energy [Kata]

1. Replace the check formula: OSR Save Target Number → 2d10 + ability >= Target Number.

• Fear: 2d10 + Courage >= 13 (on failure, Defenseless for 1 round)
• Petrification/Sleep: 2d10 + Physique >= 15 (on failure, cannot act for 1 round)
• Charm: 2d10 + Presence >= opponent's Presence + 10 opposed check
• Breath: after a 2d10+Courage+Archery(or Sorcery) hit check, everyone in the zone takes 2 Wounds; ignores cover

1. Adjust Domination: Units with powerful special abilities receive Domination +1. Abilities with a "large cost" (such as activating by spending own Wounds -1) receive no modifier.

Conversion Example — Red Dragon's Breath Weapon:

• Original: cone area, damage dice per HD, 3/day
• Conversion: [Kata] Flame Breath (4 Energy, 1/combat). 2d10 + Courage + Sorcery >= Defense check, everyone in the target zone takes 2 Wounds + fire environment(until the next round). Ignores cover. Works on yoma and incorporeal beings.

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#Monster Conversion Examples

#Oni (鬼) ← Ogre (4+1 HD)

Wounds 4, Defense 14, Energy 10. Courage+3, Finesse+0, Physique+2. Oni kanabo(3 Energy, 3 Wounds on Critical Hit). Special: "Oni's Roar" — at lull, adjacent squad Cohesion -1. Domination +4.

#Tengu (天狗) ← Harpy (3 HD)

Wounds 3, Defense 13, Energy 9. Courage+1, Finesse+2, Physique+0. Tengu fan(2 Energy). Special: "Flight" — move from Outside Zone to anywhere, or anywhere to Outside Zone, for 1 Energy. "Charming Song" — 2 Energy, target cannot act for 1 round if they fail the Presence opposed check. Domination +2.

#Onryo (怨靈) ← Wraith (4 HD)

Wounds 3, Defense 15 (no material form), Energy 8. Courage+2, Finesse+1. Hand of Grudge(2 Energy, [Incorporeal] — §Exorcism Exemption Table applies). Special: "Incorporeal" — when hit by a physical attack, d100 01~50 negates. Characters with the Exorcism skill are exempt from negation. Domination +3.

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OSR's vast roster of monsters can be brought into Konsei Reiyotan.