The manga starts from a love square. Seri is Kou-chan's neighbor, and is secretly in love with him. He has an older sister, Nana. Kou has feelings for Nana and would like to confess soon. Ikushi, Seri's friend, says he likes Nana. Seri and Ikushi get stuck in a closet by Nana, convinced that she is doing him a favor, so that Seri declares herself to Ikushi while they are alone. Seri worried, go and force the door to save them. During the summer festival Kou, after being with Seri, goes to Nana, and the girl, after an argument, asks him to become her boyfriend and toshow him what true love is.

Kou stands aside, he would then like to declare himself, because he thinks it's something that the boy should do and not the girl. Seri doesn't take it well, telling him that her sister is fickle and falls in love easily.
Seri tells Nana the wrong place to meet Kou and leaves her waiting in vain.

Ikushi finally declares himself to Seri, but she rejects him. Kou invites Nana, Seri and Ikushi to go to an amusement park. Kou and Nana kiss after an argument and while Seri is looking for them he sees the scene.

Ikushi reaches Seri.
Seri, after trying not to cry, is overcome by emotion and puts her heart at rest on the Kou issue. He also clarifies with Nana and finally reciprocates Ikushi, realizing that Kou was consciously unattainable and how much Ikushi's closeness has affected his heart.

A nice single volume, it mainly deals with first love which is sometimes just an idealization of a person and doesn't really just represent the feeling.
The ending that also plays on the possibility that Ikushi could have moved away was nice, for a moment I kept Seri alone. A pleasant happy ending.