Married to her husband for 3 years, Rika Omi's husband is increasingly busy with his work, no longer taking care of her like in their newlywed days, leaving her to suffer in a situation of being married but feeling alone. One day, Rika's husband received a flyer about a swimming class, he thought his wife might feel lonely being home alone, so he gave it to her, telling her to go there to learn. Little did he know that in that moment, he was unintentionally creating his own future infidelity.