Tragedy strikes when Emili is shockingly murdered by a mysterious stranger. The other four girls present at the scene of the crime - Sae, Maki, Akiko and Yuka - are unable to remember the killer's face and the crime goes unsolved. Fifteen years later, a now adult Sae is paid a surprise visit on her wedding day.

Fifteen years since the murder of her daughter, Asako is still overtaken with grief and resentment. One day she receives a vital new clue as to the identity of Emili's killer and sets out to find him. As she closes in on the truth, Asako finds herself in an unexpected location from her past.

Maki is now a teacher at a strict elementary school and trains in self-defense techniques to combat her feelings of helplessness. When an attacker arrives at her school, Maki jumps into action to confront him, triggering a chain of unforeseen repercussions.