Following her father's job transfer overseas, Konatsu Amano moves to Iyo-Nagahama to live with her aunt. On her way there, she is drawn into her new high school's aquarium club open house event, where she meets Koyuki Honami, an attractive senior. Through coincidental encounters, the two form a deep connection. Hoping to grow closer to Koyuki, Konatsu joins the aquarium club, which had previously been Koyuki's alone.
Both Konatsu and Koyuki share a profound sense of solitude, kindness, and consideration. However, their reserved and stubborn nature prevents them from openly expressing their emotions, straining their relationship. To move forward, they must understand their significance to one another and learn to manage their feelings. Can Konatsu and Koyuki overcome their reluctance and face their true selves and each other, or will isolation remain their only companion?