Comments of Ningyo no Hanako

4 Chapters (Cancelled due to author death)

After living in Tokyo for a while, Shirou moves back to his hometown in Megafloat 560, a man-made island where humans and mermaids coexist. Although it has been 4 years since the accident, he is still haunted by the death of his best friend, a mermaid named Tami.

aww it's completed, I wanted to know more of their backstories but it was a refreshing read

So basically it's a human on an artificial island with a bunch of good-looking fish ladies. He also loved some other mermaid but she died. That's the premise since the summary right now is pretty garbled.