Mirei, a freshman who is undecided about which club to join at school, is Kokoro by Saya's round, large hips while she is training with the tennis club one day. Mirei immediately submits her entry form to join, and Saya, a hardcore lesbian, presses her lips against hers. After a passionate kiss that almost sucks her tongue, Saya makes Mirei perform cunnilingus on her face, even though it is the club room. They start with cunnilingus on her face in the nurse's office, followed by tribadism, and mutual fingering in the classroom. Mirei becomes more and more addicted to lesbian acts, but...