Rika is a married woman who has been married to her husband for three years. Compared to when they first got married, her husband has become much busier, and now he barely pays her any attention at all. Feeling lonely about this, Rika tries to persuade her husband that it would be okay to just go for a walk, but he doesn't take her seriously. What's more, he takes out a flyer from this morning and hands her an information page about swimming lessons, telling her to attend if she has free time. Rika is shocked by the misunderstanding between her and her husband, but decides to attend swimming lessons. Little does she know that this decision will upset their relationship.