After her father relocated abroad for work, Konatsu Amano came to Iyo-Nagahama to stay with her aunt. While heading to her aunt’s home, she is pulled into the open house event at her new high school’s aquarium club. There, she encounters Koyuki Honami, a beautiful older student. After several more chance meetings, the two girls quickly develop strong feelings for each other. Hoping to grow closer to Koyuki, Konatsu signs up for the aquarium club, which up until then had only Koyuki as a member.
Konatsu and Koyuki share many similarities. Both experience a deep sense of loneliness, are gentle and considerate, yet also reserved and obstinate. These latter traits make them reluctant to open up about their emotions, creating tension in their friendship. To move ahead, the girls must come to understand what they mean to one another and learn to handle their feelings. Will isolation remain their only constant, or can Konatsu and Koyuki summon the courage to confront themselves and each other?