Six half manga

Six Half summary:

From JShoujo Scans: Kikukawa Shiori wakes up from a motorcycle accident only to find out she's lost her memory! Try as she might, she can't remember anything about the yankee-looking boy who claims to be her boyfriend, her kind-hearted and good looking older brother, or her aloof and introverted younger sister. When she goes to school for the first time since her accident, she overhears people talking about her---and the things they say aren't flattering. From what she hears, she was a terrible person before the accident. Was she really as horrible as they're making her out to be? And will she ever get her memory back?