One day, Yuki, who lives alone, meets a married woman, Nao, at a nearby pub. He had a falling out with his girlfriend's husband and ended up drinking with her at a loss, but... After that, he became friends with her, and before he knew it, he began to have a physical relationship with her. Yuki gave Nao a duplicate key to her house, and when her husband left for work, Nao started heading to Yuki's house with her shopping bag in hand. Then, as if to relieve the loneliness of being a married couple, she begins to spend a lot of time in his younger boyfriend's room...