When Kazuya hears that his mother's friend Umi, who helped him study during his school days, is returning home for the first time in a long time, he can't contain his joy. When he meets Umi again, she is even more beautiful than before... Kazuya's secret feelings for her have not changed, and they get carried away and have a relationship. Umi is carried away by Kazuya's carnal desires, and they passionately desire each other. However, she thinks that such an extraordinary relationship cannot last...