A detective and caretaker of the Protagonist. Ryotaro is Nanako's hard-working single father, but mostly spends his time away from family due to the murders. Adachi is his partner.

He is obsessed with a hit-and-run that killed his wife, and continues to investigate it, to the neglect of his daughter. His social link culminates with him coming to the resolution that he was running away from his fatherly duties by using the case of his wife's hit-and-run as an excuse because he was scared of being a father to Nanako, who reminds him of his late wife.

He is the Social Link for The Hierophant Arcana.