Always calm and composed, never showing much emotion, Satoshi Hiwatari is a distant, cold, and silent character, though these qualities never seem to affect how close he keeps to Daisuke Niwa. He is extremely intelligent and has a college degree. However, he attends Daisuke's Junior High School in an attempt to have a normal life. He acts as the police commander in charge of capturing Dark.

Due to his family legacy, he is almost obsessive in his attempts to capture Dark. He is the sole living member of the Hikari family, whose artworks are almost always Dark's targets for stealing. Satoshi recreates one of Daisuke's paintings during the incident with the Toki no Byuushin, claiming that he can mimic any piece if he sees it once. His reproduction is a precise imitation, impossible to tell from the original.

He was adopted by a 26-year-old police officer by the name of Hiwatari, and so his name was changed to reflect his adoption. During the course of the story, he begins to care more about Daisuke's safety. It appears that Daisuke is the trigger for Satoshi's other personality, Krad, to appear. Satoshi opposes Krad taking control of his body greatly, and has taken on an uncaring personality to "seal his heart," and thus, Krad. Krad is Dark's "evil twin," or opposite, a homicidal blond whose only motivation seems to be getting rid of Dark.