"The first one to cum gets to go down… how about that?" Seiji and Kazuki, who share a house rent to save money, have known each other since kindergarten and were supposed to be best friends– only their relationship changes drastically when Kazuki declares that he will get out of being virgin through sex. Seiji then replied, "If you want to get laid then I'll help you," and somehow they ended up becoming each other's "cohabitants"?! Knowing the fact that Seiji hadn't had his first experience yet, Kazuki decided to go along with it, thinking that he didn't want to get ahead of him. When the time comes for them to have sex, Kazuki, who has more experience than Seiji in terms of love, tries to take the lead, but Seiji won't just give up on Kazuki's toughness…!