After the remarriage of her mother, Yuzu is beyond upset when she finds out the conservative girls’ school she’ll be attending won’t land her a boyfriend anytime soon. After she gets a humiliating scolding from the diligent, aloof student council president Mei on her very first day, things couldn’t possibly get any worse for Yuzu — until she finds out none other than Mei is to be her new step-sister, and they’ll be living under the same roof. Oh, and Mei sexually assaults her a couple of times, but the official summaries conveniently forget to mention that.