Two girls sneak into an old swimming pool without permission. Thinking of her friend Makoto, who is depressed due to family circumstances, Mio invites her to the pool, which is open in the middle of the night, to cheer her up. There, Mio confesses her love for Makoto and Makoto spends the night with her at the pool, crossing the line. However, the pool turns out to be a training center run by a prostitution group to lure girls. Once captured, the two are tortured one after the other in order to be sold as slaves and are trained by the men to become fine sex slaves...