Megami Tensei Wiki
"I'm afraid it did not turn out as we expected..."
—Igor, Persona 3

Fusion accidents (合体エラー, Gattai Eraa)? are a hazard that can occur during fusion. This can either result in the loss of all component demons, or may result in something unexpected. Some races of demons can only be obtained via fusion accidents, often under specific circumstances. In many cases, fusion accidents ignore level restrictions.


Game-specific Rules[]

Shin Megami Tensei II[]

There is a rare chance that a fusion accident will happen, resulting in a different demon.

Shin Megami Tensei III: Nocturne[]

There is always a low chance of it happening with regular fusion; however, the odds of fusion accidents greatly increase in Full Kagutsuchi phases, though special fusions and Fiend fusions are immune. If the fusion accident results in a demon you already possess, that demon will be replaced by the new demon.

Shin Megami Tensei: Strange Journey[]

A fusion accident immediately occurs with the Copernicus sub app, while Fracastoro prevents it. Using Copernicus with Zealot summons increases the chances of getting a Zealot demon.

Shin Megami Tensei IV[]

Generally, the chance of a fusion accident occurring is low (1/64), but fusing dead (0 HP) and/or Foul demons will increase the odds: each dead demon used increases the chance by 1/64, while including a Foul doubles the final chance, for a maximum chance of 6/64. When a fusion accident occurs, the result is typically within ~5 levels of what the normal result would have been, and the skill repertoire of the resultant demon is randomly selected from its default skills and its components' skills, except those of the Famed race, which are guaranteed to have their default skills. Most Famed race demons and Undead Corpse can only be created via fusion accident.

Shin Megami Tensei IV Apocalypse[]

The mechanics for intentionally creating a fusion accident have been tweaked a bit since the previous game. In addition to using a 0 HP and Foul race demon to increase the chances, having Nanashi inflicted with the Sick ailment increases the base chance from 1/64 to 6/64, and each demon inflicted with the Sick ailment increases the chances by 3/64, allowing the one to increase their chances of an accident to the maximum by having Nanashi and two demons sick, one of which is Foul race, to 3/8 [(6/64 + 3/64 + 3/64) x2]. Once again, the majority of Famed race demons can only be created by fusion accidents, along with Undead Corpse and Zealot race demons.

If the player wishes to deal with the hassle, though Unique skills cannot normally be passed on through any type of fusion, with the except of a small select few through Fusion Lite, they can all be passed on via fusion accident.

Shin Megami Tensei: Devil Summoner[]

Fusion accidents may occur while fusing at Hotel Gouma-Den at a low chance (1/256), which can be increased by fusing demons of the same race together with two of the same race resulting in a 1/32 chance and three resulting in a 1/16 chance.

Demons of the UMA and Enigma-races can only be obtained through fusion accidents, the former by using any of the Beasts family demons during a Full Moon and the latter by using any of the Gods family demons during a New Moon.

Devil Summoner: Raidou Kuzunoha vs. The Soulless Army[]

A fusion accident in this game will result in one of five different types of Legion demon. Once forge fusion has been introduced in Episode 3, Victor will mention that the machines have become a bit unstable. Utilizing unstable fusion by using a Skill Order demon during a Full Moon will yield the best chance of causing a fusion accident. The level of the demons have no bearing on the result, with Ippon-datara and Ukobach being able to bring forth every Legion variant when an accident occurs.

Once the demons to use in the fusion attempt have been prepared by maximizing their Loyalty, Raidou can check in at the Narumi Detective Agency immediately when the moon phase reaches a Full Moon and have enough time to run directly to the Gouma-Den before the moon phase changes, allowing for easy retries should an accident not occur.

Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon[]

When fusion accidents occur, it will become one of three demons: Fury Order Slime, Skill Order Blob or Frost Order Black Ooze. If one attempts Fiend Fever or Evil Fever fusion and have all the demons of those orders on them, then one of the three slime demons will then be the result.

Megami Ibunroku Persona[]

Personas of the Fool Arcana can only be created through fusion accidents. The other possible results are that the persona will be chosen at random from a different Arcana, the Persona will gain or lose stats, or will randomly inherit a skill from one of its "parents."

To guarantee a fusion accident resulting in a Fool Arcana persona, the player can take 101 or 230 steps from a "hard reset" (as in, not already mid-game and loading a save or selecting "Return to Title;" the player must exit the game to reset the Random number generator) in an area where no enemies will attack, such as the Mikage Sun Mall (for an odd number of steps) or the Black Market (for an even number of steps), and performing a White Fusion, or by taking 275 or 546 steps and performing a Red Fusion. As the lowest level Fool is level 30, the protagonist must first be at least level 25.

A fusion accident resulting in +2 to all stats can be guaranteed by taking 6 or 25 steps and performing a White Fusion, and a random skill inheritance accident can be guaranteed by taking 31 or 62 steps with a White Fusion or 21 steps with a Red Fusion.

During the Snow Queen Quest, steps inside the infirmary count towards the number of steps for forcing a fusion accident. As such, it is possible to do any of the confirmed accidents since the player can take one or two steps prior to leaving the infirmary, allowing both even and odd step fusion accidents.

This works when using Totems and Gems, but not Skill Tablets or items, so any extra skills wanted on the end result must be from inheritance. As Skill Inheritance functions as normal, it is likely that Unknown Powers do as well.

Persona 5 Royal[]

During a fusion alarm, if the protagonist does two executions in a row using the same device (Guillotine, Electric Chair, or Gallows), a fusion accident will always occur. Fusing a Persona that was just fused during the same fusion alarm instance (their name will be in gold as long as the protagonist is in the Velvet Room) will always trigger a special fusion accident, giving the protagonist the desired Persona, but with a random, often incredibly bizarre or specific set of skills.

Persona 5 Strikers[]

A Persona fused as a result of a Fusion accident will always match the level of the protagonist, ignoring the base level of the fused Persona. A Fusion accident also grants a substantial amount of bonus stats in the form of accumulated power, which can be inherited by Fusions that use the accidental Persona as a material.

Dungeon - Combat - Turn - Action - Level - Experience - Party - Stats - Skills - Items - Equipment - Melee Attack - Ranged Attack - Damage - Guard - Escape - Accuracy - Critical - Multi-hit - Insta-Kill - Ailments - Drops - Encounter - Random Encounters - Symbol Encounters - Ambush - Difficulty
Demon - Magic (Fusion Spell) - Affinities - Unique skills - Extra Skills - Macca - Yen - Magnetite - Incense - Alignment - Moon Phase System - Demon Summoning Program (COMP) - Cathedral of Shadows (Fusion - Skill Inheritance - Accidents / Special / Three-demon / Sacrificial / Sword) - Demonic Compendium - Evolution - Negotiation (Special conversation) - Rag's Jewelry - Code Breaker - Press Turn - New Game Plus - Ultimate boss - Streetpass - Password - Skill Mutation - Energy Drain - Party Talks
Shin Megami Tensei series
Terminal - Guardian (if...) - Tactical Battle (NINE) - Capacity (NINE) - RTS (NINE) - Reinforcements (NINE) - Race Shift (NINE) - Modules (NINE) - Magatama (3) - Reason (3) - Demon Co-Op (SJ) - EX Missions (SJ) - Challenge Quest (4) - Skill Potential (4/A-5) - Smirk (4) - Barrier (4) - Partners (4A) - Jade Dagger (4A) - Magatsuhi Skills (5) - Essence (5) - Glory (5) - Miracles (5) - Demon Statues (5) - Abscess (5)
Devil Summoner series
Loyalty - Personality - Mystic Change - Nemechi (SH) - Case Files (RKKA)
Majin Tensei series
Rank - Affinity (2) - Arcana (Ronde)
Persona series
Shadows / Personas (Initial / Prime / Ultimate / Ancestor / Reverse / Sub) - Skill Card - Totem (1) - Type/Subtype (1+2) - Affinity (1+2) - Rank (1+2) - Mystic Change (1+2+5) - One More (3-5) - Growth Rate (1+2) - Unknown Power (1+EP) - Personality (1+2, 5) - Material Card (2) - Mutation (2) - Follow Up - All-Out Attack (Cut-in) - Heart Item (3) - Shuffle Time (3+4) - Daily Life (3-5) - Calendar (3-5) - Social Stats (3-5) - Social Link (3+4) - Tactics (3-5) - Requests (3-5;Q+Q2) - Arcana Chance (4) - Forecasts (Fusion / Weather) (4+5) - Boost (Q+Q2) - Power Spot (Q+Q2) - F.O.E (Q+Q2) - Confidant (5) - Technical (5+5S) Treasure Demon (5+5S) - Party Switch (5+5S) - Disaster Shadow (5R) - Fusion alarm (5R) - Persona Traits (5R) - Third Eye (5+5S) - Master Arts (5S) - BOND (5S) - Persona Points (5S)
Devil Children series
Trainer - Bank - BattleNet - Relic Fusion - Power Fusion - Powers
Digital Devil Saga series
Berserk Mode (2)
Devil Survivor series
Devil Auction - Extra Turn Battle - Skill Crack - Titles (DSO / DS2 / RB) - Fate System (2) - Add-On (2)
Equip Type (GMT:TM) - Skill Systems (GMT:TM) - Sword Exchange (GMT:TM) - Class Change (TMS♯FE) - Topic System (TMS♯FE) - Side Quests (TMS♯FE) - Ad-lib Performance (TMS♯FE) - Session (TMS♯FE) - Dual Arts (TMS♯FE)