Sister Breeder is a hentai anime adaptation of the manga Sister Breeder by popular author Takeda Hiromitsu. men is very attached to his sisters Rene and Aina. Every day, he becomes more and more attached to Aina… and eventually he even sneaks into her room at night! Rena tries to stop men, but ends up having sex with him instead of Aina. Due to her hidden feelings for men and the pleasure of new sensations, the once innocent Rena gradually becomes addicted to sex…!?