The Boxfish and the Sea of Minamata

Overview

The boxfish has no confidence in himself, he always spends his time alone on the rocks watching the other fish, feeling envious. "Everyone else is so lucky. All I do is float back and forth in the same place on these rocks every day..." Then one day, he meets a lost sea horse who seems to have come from the Minamata ocean, he then decides to embark on his first ever adventure to return the fish to the Minamata's sea... (Source: Official Website, translated)

Source: AniList