Shin Megami Tensei [KAHN]

Nobu is a troubled teenager with a difficult history. His former high school was absorbed into the Underworld, where he and his classmates fought against demons commanded by Hazama, the Demon Lord. Nobu and Yumi, a girl possessed by a demon, managed to return to the Surface World, seeking to begin fresh lives in new schools. Soon after, Nobu learns about a government plot to bring about destruction on Earth, drawing him and Yumi back into a dangerous conflict with their fears.