The Matsumoto couple have returned to the husband's parents' home. Mei, the wife, has had a question since the beginning of their marriage. It was about her brother-in-law, Naoki. He has been living as a recluse in his room on the second floor for the past four years. Mei is so anxious that she can't fall asleep until late at night, and when she goes to the kitchen alone for a drink of water, something strange happens...