Housewife Sasamoto Sawa works as a part-time supermarket cashier. One afternoon, she unconsciously pickpockets a lipstick at the supermarket. Takigawa Rikako sees a part of this. What she proposes is Sawa’s assistance in setting up an alibi for her affair in exchange for her silence on that matter. Sawa obeys the demands of Rikako in order to protect her “happiness” even though she is falling apart emotionally. In the process, she meets high school teacher Kitano Yuichiro and gradually cannot stop thinking about him. Before long, she crosses a line which she should not.