Yuma Kokohead is amnesiac. He lost his memories after making a pact with Shinigami, a death god in exchange for his memories, which he can't talk about with anyone, otherwise the pact will be broken, so Yuma never talks about Shinigami with anyone. Yuma suffers from amnesia. His background is unknown, but he was in possession of documents indicating that he was sent to Kanai Ward as a detective-in-training at an agency in the city. He participates in ongoing investigations.