The beautiful mermaid I fell in love with became human but when she transformed she became… a man? Manato Koganei, a part-time worker on the brink of despair meets a beautiful mermaid shining in the moonlit night?! She says she wants to "become human and fall in love", and is successfully reborn as a very beautiful man. Manato tangles with his own feelings for his former mermaid, now human companion while also trying to help him navigate human culture. Will they fall in love or will their love sink to the bottom of the ocean?