From Yuri Project:

Fashionable Yuzu imagined the first day at her new school she transferred to after her mother’s remarriage a bit differently; she didn’t know it’d be an ultra-strict and conservative girls’ school. So instead of a sweet high-school romance, she butts heads with the stern student council president Mei – who turns out to be her new step sister. And she has to learn that hate and love are often not that far apart.