When Hitomi was 20 years old, she got pregnant with a boy with a man who had a wife and children. The man asked him to drop her, but Hitomi disappeared from the man's sight and gave birth to Tatsuya alone. Hitomi and Tatsuya became close friends rather than parent and child. Hitomi harbors an old love for Tatsuya, who is becoming more and more like her father. And when Tatsuya was a student, he finally crossed the line. When Tatsuya turned 20, Hitomi invited him to a hot spring trip to celebrate.
