Yusuke, who is teased by his classmates for being a virgin, spends his days in frustration. His mother Yukaka, worried about her son's depression, tries to boost his confidence with kind words, but to no avail. Unable to bear it any longer, Yukaka offers herself, becoming the partner for her son's first sexual experience. What started as sex education for Yusuke's benefit turns into him becoming dependent on his mother's body…
