Hinata who thinks of her younger brother. In order to fulfill my younger brother's dream of becoming a regular member of the swimming club, he spends his days being embraced by his adviser Oni-sensei. My virginity was stolen by a teacher! I don't like it anymore and want to end this relationship, but my teacher threatens me and I can't quit... my teacher won't give me a rubber band, so I'm afraid I might end up having a baby... actually, I'm having sex with my teacher. Hinata-chan, who feels strongly and cannot be refused, is swallowed by the whirlpool of pleasure. The forbidden pact continues...