Devil Children Black Book & Red BookEdit
The Shady Manor is exclusive to Black Book, while the Shady Laboratory is exclusive to Red Book. Both facilities perform demon fusion, but in different ways.
In both versions, fusing any demon with Cool or Veil will strengthen the protagonist's partner by increasing their stats. Not only that, the partners can level up by absorbing experience points from the demons used to strengthen them, thus increasing their stats even higher. However, the partners cannot go more than five levels above the protagonist.
The Shady Manor is run by Franken. He performs Racial Fusion (種族合体, Shuzoku Gattai)?, in which two demons of different races are fused together to create a demon of a different race than the ingredients. The resulting demon is determined by which races the demons belonged to and their levels.
The Shady Laboratory is run by Parallel Sus, who can perform Pure Blood Fusion (純血合体, Junketsu Gattai)? and Mixed Blood Fusion (混血合体, Konketsu Gattai)?. Pure Blood Fusion consists of fusing two of the same demon together, which increases their maximum HP and SP. There's also a chance of unlocking the demon's hidden skills. Furthermore, certain demons can evolve if strengthened enough times.
Mixed Blood Fusion consists of fusing two different demons together, with different results depending on the order in which demons are fused and their level. When fusing a demon with a second demon of lower level, the first one will be strengthened and have their stats increased. If the second demon is of a equal or higher level, the first demon will transform into a higher-leveled demon of the same race.
When transforming into a stronger demon, if the original has a stat higher than the resulting demon (as a result of being strengthened many times), that stat will be kept. If the second demon is of a much lower level, fusion is not possible. Although demons other than Veil do not explicitly level up, they do have a hidden "level up" attribute that prevents them from being strengthened too many times unless Mirai levels up.
Boss-race demons are special in that they will always be strengthened, even if their fusion partner is of a higher level. As there's no way of acquiring multiple copies of the same Boss demon outside of trading, the only way to increase their HP and SP is via the use of Trainers.
Devil Children White BookEdit
Partner strengthening works the same way as the previous games. Both Franken and Parallel Sus are present in the game, giving the player access to all three kinds of fusion. However, they're not always present in the same town: some of them may only have one or both in the same building. There's at least one town per world visited with both facilities.
In the Deep Hole, Dian Cecht can also perform the Infrared Fusion (赤外線合体, Sekigaisen Gattai)?. As the name suggests, this fusion makes used of the Game Boy Color's infrared sensor and requires the player to aim any kind of infrared light at the Game Boy's sensor during the fusion process. Infrared Fusion follows the same principles of Franken's Racial Fusion, but the resulting demon will be transformed into a higher-leveled demon of its race.
|Playable||Mirai Kaname - Setsuna Kai - Cool - Veil|
|Non-Playable||Nagahisa Kai - Elegy - Zett Takajō - Lucifer - Azel - Hoshigami - Zebul - Michael - Diana - Dust - Paimon - Isis - Souta - Hel|
|Expanse||Ice Land - Marble Land - Sand Land - Forest Land - Fire Land - Central Land - Sanctuary - Deep Hole|
|Other||Vinecenter - Shop - Bank - Hotel - Casino - Trainer - Shady Laboratory & Manor|
|Songs||Go-Round - LOVE SICK - Tenkai no Aurora ~ AURORA HEALING - Idol ~IDOLL~|
|Terms||Devil Riser - King Riser - Macca - Magnetite - Expanse - Devil Child - Angel Child - Devil Database - Devil Phone - Keys of Norn - Vinecom - Type|
|Lists||Items - Demons - Skills - Status Changes|
|Productions||Shin Megami Tensei: DeviChil|
|Playable||Masaki Kuzuha - Clay|
|Non-Playable||Takaharu Ougi - Rei - Shou Ougi - Paku - Haamiru - Setsuna Kai - Mirai Kaname - Cool - Veil - Takajo Zett - Nathanael - Raguel - Lucifer|
|Expanse||Earth Expanse - Wind Expanse - Ice Expanse - Deep Hole - Center Expanse - Grass Field - Crystal Ring - Cosmos City - Altimia|
|Terms||Devil Riser - King Riser - Macca - Magnetite - Expanse - Devil Child - Angel Child - Devil Database - Devil Phone - Vinecom - Power Unit|
|Lists||Items - Demons - Skills|