Satoshi is the missing older brother of Satoko whose disappearance is the trigger behind the actions of several characters in the various arcs of the series. He was shown to be the emotional support for Satoko when they were adopted by their abusive aunt and uncle following the deaths of their parents. Satoshi was shown to be a talented baseball player for the local team and was on the receiving end of a crush from Shion. It is strongly implied that the pressure of caring for Satoko and believing that he was responsible for his aunt's murder drove Satoshi to run away. Shion was the last person to have seen Satoshi as he told her to take care of Satoko if he were to disappear.