Best friends Haruka and Yu have finally started high school only to find out it will be closing when they graduate. To ensure that Yu remains closest to her, Haruka decides to explore their friendship further and kisses Yu. With their friendship strengthened they go throughout the rest of high school with a bond only the closest of friends can share.
Haruka and Yuu are the best of friends, but when they get to high school and that bond is tested, they become something more.
Harua and Yuu stumble into a special moment between their two friends. Haruka vows to not let Yuu fail for the year in any way she can.
Haruka petitions the student counsel to allow a cheerleading squad at the Ball Sports tournament for Yuu. Later the girls clean the school pool in order to get first dibs on it when swimming season starts.
Yu's sister becomes suspicious of Haruka and Yu's relationship, and enlists their friends to spy on them. Later, a test of courage proves to be too difficult to overcome for Yu and Haruka late one night.
Haruka and her friends try to ask Mitsuki for a favor, but are thwarted when Yuu and the rest of the group show up. Later, Mitsuki is caught snooping around and is thrust into the role of Snow white in the school play.
The girls decide to spend the night at school to finish up their Culture Festival projects. Later, Haruka gets angry at Yuu for standing her up.
The girls spend some time having fun in an indoor swimming pool. Later, Yuu and Haruka go shopping for the perfect scarf for Yuu.
Haruka invites Yuu to a relative's wedding, but the invitation is misconstrued as a proposal. The group takes a trip to a light art show, but Mitsuki senses that her sister and Haruka seem distant, and so goes out of her way to help.
New Years is fast approaching, and Haruka has a nice phone chat with Yu to celebrate. Later, Mitsuki becomes jealous of her sister linking arms with Haruka.
Haruka challenges Kaede in a gym class jump rope contest. The group falls behind the rest of the class and they end up in last place. Haruka volunteers to put away the equipment and gets locked away in the storage closet.
Haruka and Yuu are caught kissing and Mitsuki forbids them kissing. Despite all of the watchful eyes upon them, Haruka and Yuu still manage to kiss each other in secret.
Yuu argues with Mitsuki about the efforts to keep her and Haruka from kissing. Mitsuki confesses her love to Haruka, but it is all for nothing since Haruka has lips only for Yuu.