There are other names later on in the series, but since they don't appear in the first chapter, let alone the first graphic novel, I won't comment. And, um, for those who are confused. I prefer using the traditional way of writing names. Namely, last name first. So in English, Kagome's name would be Kagome Higurashi.
Mermaids are creatures of legends.
Each book contains 3 chapters of the life of an immortal named Yuta. Yuta is a man who ate the mermaids' skin over 500 years ago. In each book, Takahashi jumps back and forth between Yuta's past and present. This is an interesting way to unfold his life and personality. It is also a great way to present the horror behind the legendary creature.