Haruto "Haru" Touma dies in an absurd manner, bowled over by a black cat falling out of the sky and knocking his head against the pavement. After his soul leaves his body, he is approached by an angel who apologizes for killing him by mistake! Apparently this angel, Shiro, is the partner of the black cat, Kuro, who is actually a shape-shifting demon. The two are looking for a young human destined to die soon who they can turn into a "shinigami." Although Haru's death was by accident rather than fate, they decide to take advantage of the situation and extend their offer to him.

Six months prior, Haru had lost both his family and memories to a traumatic fire set by an arsonist. Unable to recall his parents and sister, he could not properly mourn them, so he lived his life with a sense of detachment and feelings of guilt. After learning of Haru's personal history, the angel and demon decide to sweeten the deal: if he cooperates with them as a shinigami and collects the souls of sinners who have escaped Heaven, then when all is done, it may be possible to return him to the day of the fire so he can regain his memories. With that incentive, the contract between them is sealed, and in his afterlife, Haru gains a reason to live that is stronger than any conviction he had while still alive.