Haruka and Yuu are as intimate as ever as it turns to summer, but Yuu has been worried ever since Mitsuki saw her and Haruka post-kiss shortly ago. Mitsuki has been prying into their relationship ever since.

Sonoda Mitsuki, Yuu's big sister and acting student council president, become curious what "Takayama Haruka," the girl Yuu keeps bringing up lately, is like. Meanwhile, Haruka and the others are shocked to learn that due to the number of students and costs, a small-scale ball sports tournament will be held instead of a sports festival.

Takayama Haruka's heart fills with hope that she'll be in the same class as her best friend Sonoda Yuu as she prepares to start high school the next day. Aside from Yuu, her class is full of unique girls like Kotone, Shizuku, Kaede, and Yuzu.