Shokuzai

A young girl, Emili, is killed by a stranger in elementary school. Although her four friends saw the suspect, they say they don't remember it. 15 years have passed and the incident is still unsolved. Emili's mother, Asako (Kyoko Koizumi), makes them do penance for it. The series focuses on the psychological repercussions on each of the four girls, 15 years later. (wikipedia)