Ichiko is a devoted in-home caregiver for a family she has almost became a part of. While Ichiko cares for the grandmother, she is also a confidant to Motoko, the eldest sister in the family. One day, Motoko's younger sister disappears and was found shortly after. The media soon reveals the kidnapper to be Ichiko's own nephew. Ichiko's life changes dramatically when her secret past is revealed to the public by Motoko's action; by the only person who supposedly supported Ichiko. Everyone starts to distance himself or herself from Ichiko as she loses her job unlawfully over the crime her nephew has committed. On the surface, Ichiko is both a perpetrator and a victim, but the truth does not convey to the surroundings. Instead, everything spins out of control. The struggle and the frustration wrecks her. A few years have passed. As if trying to open an old wound, Ichiko returns to the town where she used to live. She spots Motoko, the person who ruined her life. Could it be a sign of liberation or is it the beginning of further destruction? What did Ichiko and Motoko commit, and what is their sin?