Shin Megami Tensei III: Nocturne

In Shin Megami Tensei III: Nocturne, the player takes on the role of a young boy who is caught up in The Conception while visiting his sick teacher, Yuko Takao, with his two classmates Chiaki Hayasaka and Isamu Nitta. The young boy is transformed into a demon known as the Demi-fiend and he must survive in the newly created Vortex World with the powers granted to him through Magatama.

Summary: IGDB