A Tropical Fish Yearns for Snow Vol. 7 (manga)

Konatsu senses that she and Koyuki, the only two members of the Aquarium Club, are connected by loneliness, and she's afraid that her bond with Koyuki is weakening as it gradually changes. When Konatsu's feelings finally erupt, Koyuki resolves to face her head-on, leading to a clash of feelings before the girls can confirm how important they are to each other.