When Konatsu Amano's dad finds a job abroad, she has to leave her life in Tokyo and move to a small seaside town to stay with her aunt. The change also means she has to start at a new school, surrounded by brand new people, which is quite difficult for a girl who has trouble with change.

On her first day in her new town, Konatsu immediately comes into contact with Koyuki, an older girl who is the only member of the Aquarium Club. Konatsu's introverted tendencies are hard to overcome, but she might have found something worth coming out of her shell for.

Konatsu feels that she and Koyuki, the only two members of the Aquarium Club, are connected through loneliness, and she fears that their bond is starting to weaken as their feelings gradually change. When Konatsu's emotions finally explode, Koyuki decides to confront them directly, leading to a clash of feelings before the girls can confirm how important they are to each other.