Hitomi became pregnant with a boy at the age of 20 by a married man. The man asked her to have an abortion, but Hitomi disappeared from his sight and gave birth to Tatsuya alone. Hitomi and Tatsuya had a relationship more like friends than mother and son. As Tatsuya grew more like his father, Hitomi began to harbor old feelings for him. Eventually, when Tatsuya was still a student, they crossed the line. When Tatsuya turned 20, Hitomi invited him on an onsen trip to commemorate the occasion.
