In a row of wooden municipal houses in the countryside, Hidenori Yamane (Tadanobu Asano) & Nanase Ogawa (Minami) lives together under the same roof. The roommates co-exist in a tense & awkward state. Every night Hidenori hides in the attic and peeks through a hole into Nanase's room, while thinking of the cruelest ways to inflict revenge. Meanwhile, Nanase, who wears outdated sweaters and glasses, refers to Hidenori as her "brother" (even though they are not related) and is aware he is peeking at her at night. They sleep on the same bunk bed but do not have sex. There was a case that happened 10 years ago and since that time Nanase awaits for the worst form of punishment. One day, a couple moves into their neighborhood and a delicate crack starts to emerge between their closed off relationship.