Source is a manga called Crimsons
https://myanimelist.net/manga/35047/Crimsons__Akai_Koukaishatachi
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Source is a manga called Crimsons
https://myanimelist.net/manga/35047/Crimsons__Akai_Koukaishatachi
The character designs are something else
Well it has japanese katakana in it
Oh
slaps forehead
Of course
It's from a manga!
Case closed everybody.
And fish live in the water, so we can narrow it down to a Japanese body of water. I'd wager we're looking at the Pacific Ocean here.
Maybe some fish isekai?