Due to her father's work abroad, Konatsu Amano relocated to Iyo-Nagahama, where she settled with her aunt. During her journey to her aunt's home, Konatsu came across an open house at her new high school's aquarium, where she met the striking senior, Koyuki Honami. They quickly developed feelings for each other, after a few fortuitous encounters. In a bid to get closer to Koyuki, Konatsu joined the aquarium club, of which Koyuki was the sole member. Despite sharing qualities like loneliness, kindness, thoughtfulness, hesitancy, and obstinacy, expressing their emotions proved challenging, which strained their relationship. To move forward, they must define their roles in each other's lives and discover ways of reconciling their feelings. Will they overcome their loneliness and summon the courage to confront their inner selves and each other?