Website and data research by 101Leafy.

101Leafy researched the game to work out how fusion picks its result. Pick two demons to see what they make, or pick one demon to see every pair that makes it.

Fusion calculator

Pairs that make a demon

Every pair of two demons that fuses into the demon you pick, with the special demons set as in the calculator above. The order of the two does not matter.

Rules

1. Only demons of these twelve races can be fused: Megami, Deity, Flying Dragon, Snake, Divine, Avian, Avatar, Beast, Genma, Fairy, Kishin, and Warrior. The hero and heroine never can.
2. The race chart gives the race of the result from the races of the two demons.
3. Each race has eight demons, numbered 0 to 7 from the weakest. Add the numbers of the two demons, then add 2 for each Deity and 1 for each Flying Dragon, Snake, Divine, and Kishin. Keep the sum between 0 and 14 and halve it, rounding down. That is the number of the result inside its race.
4. A special demon only comes out after its story event has set it free, and only when no unit on the map is that demon. Otherwise the fusion gives the demon one below it. On a chain, such as the four archangels, the check goes on down the chain.
5. The game refuses the fusion when the result's level is above the hero's level.
6. When fusing on a map, the result's race must be able to move on the tile where the fusion takes place.
7. The result is a new demon with the level and stats of its entry in the demon list. Rank and battle points start again from 0.

Race chart

Row race plus column race gives the race of the result. The chart reads the same both ways.

Special demons

These demons need a story event before fusion can make them. Until then a fusion that should give one of them gives the demon named under it.

Cannot be fused

Demons of these races cannot be used in fusion, and no fusion makes them.