Yuzu, a seemingly carefree gal on the outside but pure-hearted on the inside, ends up living under the same roof as Mei, her stepsister due to their parents' remarriage. Despite Mei being the cool and exemplary student council president, Yuzu finds herself increasingly aware of Mei, especially when she unexpectedly kisses her. As Yuzu becomes aware of her feelings for Mei, she is declared by the student council vice president, Himiko, to have "crossed the line with the president." Yuzu tries to deepen her relationship with Mei, but her efforts often fall flat. One day, she touches on the emotional scars Mei carries from being abandoned by their father in the past, and Yuzu desperately tries to heal her...!?