You, Aquarist  

よぅ、アクアリスト

At a festival, a young man came across a discarded goldfish while wandering around. He remembered his childhood experience of buying a goldfish from a stall and bringing it home only for it to die shortly after. Feeling guilty for his past actions, he decided to make amends by releasing the goldfish into the river. However, a strange girl stopped him and informed him that it is against the rules to release goldfish into the wild. As a result, the young man learned how to care for goldfish as an "aquarist" and gained a newfound appreciation for these fascinating creatures.