City Hunter

Ryo notices that he is being watched by Kozue, a 12 year old girl confined to a wheelchair. When he pays her a visit, Kozue remarks that he is the second person to notice her, the first being a mysterious man with a beard. Kaori suspects that Ryo is using Kozue to get to her much older sister. But when the mysterious man attacks Kozue, Ryo decides to have Kozue and her sister live with him until he can figure out what is going on.