You, Aquarist

A boy with bright red hair and a strong appearance tries to avoid unnecessary conflict. On a summer festival day, he discovers two goldfish in a discarded plastic bag and recalls a past accident in which he killed some. Attempting to release them into a river, he is stopped by a knowledgeable girl who explains that releasing goldfish is harmful. She teaches him that goldfish should be cared for by humans, and he agrees to take them in. She visits his apartment to help him care for them. Unbeknownst to them, another girl named Mayu is watching, as she also has something to share with him about fish.