Shiho gave birth to Yuki when she was 20 years old, and her married life gradually began to change afterward. As Yuki grew older, her husband lost interest in sex, leading to a sexless marriage, while Shiho's own sexual desire intensified instead. Then one day, upon discovering her husband's infidelity, their relationship quickly deteriorated, and divorce discussions moved forward. By the time Yuki entered university, the divorce procedures were nearly complete, with only the official paperwork left to file. When summer vacation arrived and Yuki returned home, Shiho decided to inform her son about the impending divorce and headed to the station to meet him.