Ningyo no Oujisama

he beautiful mermaid I fell in love with became human. A "male" human, Manato Koganei, a part-time worker on the brink of despair meets a beautiful mermaid shining in the moonlit night (and she's all battered up for some reason)?! She says she wants to "become human and fall in love," and is successfully reborn... but with a "third leg"?!!! A non-human existence? A sex change?? BL??? Say hello to a very odd love comedy~

(Source: Coamix)