One of the original survivors of the Machida massacre alongside his young sister Saya, he joined the police force to find out who was responsible for murdering his parents. Posted as a non-uniformed officer in the Shibuya Precinct as a detective in the Tokki division, he finds out during his work that demons from the dark realm were responsible for orchestrating various massacres in order to destroy Japan. Later on, he joins the Tokko division so as to save the country from being overrun by the demons. He suffers from Post-traumatic stress disorder due to the massacre and the deaths of his parents when he and his sister were still in college and high school. He originally had brown hair, but dyed it to yellow with bits of orange after graduating from high school. His symbiont tattoo is on his right arm and a second appeared on his left shoulder after his 'awakening'.
Since he survived the Machida incident, all Phantom demons were given instruction to finish him off, as well as any other witnesses who have seen the events.
As he and Saya were the only survivors of the Shindo family, the two became very close after they were tragically orphaned. It can be inferred that he has feelings for Sakura Rokujo during the series where they are alone on the roof of a building talking of how they were glad to meet.