ある夜、下着姿の薫が助けを求めて草太の部屋にやってきた。
驚く草太だが、実は部員達が脱衣ルール付きの麻雀大会を開催しており、
敗色濃厚になった薫が起死回生の一手として草太を代理に担ぎ出しに来たのだった。
大会の優勝賞品は…草太を好き勝手できる権！？
気乗りしないが自らを守るために参戦する草太。
一方、薫は薫で思うところがあるようで…
One night, Kaori, wearing only her underwear, comes to Sota's room seeking help. Sota is shocked, but it turns out the club members were holding a strip mahjong tournament. With Kaori facing certain defeat, she makes a last-ditch effort to recruit Sota as her substitute player. The tournament's grand prize was... the right to do whatever they wanted with Sota?! Reluctant but needing to protect himself, Sota joins the game. Meanwhile, Kaori seems to have her own thoughts on the matter...
