Chapter 1 Edit
Yuzu Aihara enters her new high-school, hoping to get a boyfriend there only to realize it's a girl's-only school. Unaware of its highly conservative rules and student body, she is approached by a member of the Student Council, who points out her infractions on the school dress code and the school's policies on cellphones. Yuzu tries to make excuses, as she is a new transfer student, but she is then confronted more harshly by the council president, who takes her cell phone and says she can get it back at the end of the day.
Afterwards, after cleaning her make-up in the bathroom, she is called to class by her homeroom teacher, Amemiya, who she notes to be pretty. After the class, attempting to make friends, Yuzu asks two girls if they will be going to a mixer or karaoke after school. They look at her as if she is a criminal, much to Yuzu's shock and dismay. Another student, Harumi Taniguchi, introduces herself to Yuzu and explains to her how the school works and how to get around its rules. After school, Yuzu witnesses Amemiya and the president kissing in what appears to be assault.
When Yuzu returns home, her mother reveals that the president, Mei Aihara, is now her step-sister, much to her surprise. Once the initial shock subsides, Yuzu offers to make peace with Mei, since they were now sisters. When she is ignored, Yuzu comments about the kiss between Mei and Amemiya, suggesting that it was her first kiss. Now provoked, Mei pushes Yuzu down and kisses her, and Yuzu is left in the room alone and confused.
Chapter 2 Edit
Yuzu, Mei, and their mother go out to shop. As they traverse the mall, Yuzu reflects over the true meaning of the kiss that Mei had forced on her. After having a short conversation about Mei's family situation, she reveals that she hasn't seen her father in 5 years and that she'd been living with her grandfather, who is the school's chairman. Distracted by this new information, Yuzu trips into a fountain while dragging Mei down with her, forcing the family to go home to bathe.
The next morning, Yuzu boldly greets the chairman in a familiar manner only to find that he does not recognize her as his granddaughter, while Mei is scolded for her lack of action. Later, Yuzu and Harumi witness Amemiya admitting to using Mei's hand in marriage only for financial gain and status.
At home, Yuzu finds that Mei is already aware of Amemiya's intentions and rejects Yuzu's advice. During the morning assembly, Yuzu reveals that Amemiya had kissed a student. Once Yuzu arrives home, her mother tells her that Mei was taken away