Yuma is the latest addition to the Detective Agency, founded by former Detective Shinigami. A huge undertaking to establish a new agency, the scale of which the world has never seen. With the assistance of Shinigami, they aim to solve the most baffling cases, one of which is the disappearance of a young girl. 

The girl was last seen at a memorial service, attended by both the police and the private detective agency. Neither could provide any clue as to the girl's fate, and her friends and family are desperately looking for answers. It seems that the case holds some significance for the private detective agency, as they've brought in a trainee to investigate.