Shin Megami Tensei: Devil Children - Light & Dark

Due to family circumstances, Setsuna Kai is moving to a new city where he's supposed to live by himself in an apartment. As soon as Setsuna arrives, he witnesses a mysterious rain of rocks and barely escapes being crushed by an enormous boulder. Setsuna's new home wasn't as lucky, being completely destroyed by another giant boulder. Setsuna is distraught, not knowing what to do when he's approached by a scientist named Hiromi Kaname. Dr. Kaname's equipment apparently can tell that Setsuna is a "Devil Child", and so Dr. Kaname decides to take Setsuna to his laboratory.

The age of the demons has begun. Dr Faust has foreseen this rise of evil. Unfortunately, he is near death and is unable to personally battle this upcoming threat. Faust entrusts a young boy, Shingo Yamada, to take the responsibility of ridding the Earth of this new evil presence. Faust finds a birthmark on Shingo's forehead that signifies that he is the chosen demon fighter. Faust summons from hell what may be humanity's only hope of surviving: a less than enthusiastic devil named Mephisto rises. After signing a pact in blood to save humankind, Shingo and Mephisto set out to battle the supernatural world.

Following an accident in the Himalayas, Akira Fudou's body has been taken over by none other than the fearsome demon, Devilman. However, upon living with Akira's relatives, Devilman has come to find himself rather fond of humanity - even if it means getting roughed up by his girlfriend, the Most Dangerous Miki Makimura for acting out, much to the Demon Lord Xenon's dismay. Wishing to kill the traitor, Xenon begins unleashing a series of cruel, grotesque demons unto Earth, and only Devilman stands between them and humanity's demise. Can the reluctant hero save his soul while keeping the city and his secret identity safe?

The devil king Lucifero suddenly declares he's going to retire, and must choose a successor. The Devil King Cadets gather one after another, and go to the human world to participate in the succession contest. But only the devil king's own descendant Osamu has no interest whatsoever in the contest. Compared to the fate of the world, Osamu is more interested in his part-time job at a convenience store. Osamu has no choice, however, but to start collecting familiars called "Child," which are born from human souls. Osamu still only has an interest in his part-time job, and he's a few steps behind the rest of the Cadets.