[Doraneko]

There are two versions of UmiMono serialized in two different magazine (Comic Blade and Comic High). The other version is more of a slice-of-life story, with no fighting so far and is mainly about the funny everyday life of the mermaid sisters in the human world.

In that version, Marin genuinely wanted to return the ring to its owner and that was the major motivation for her to get to the "sky-dwellers'" world.

Somehow I feel that the anime is like a mixture of the two manga, with the plot and character design from the Comic Blade version and the slice-of-life essence from the Comic High version.