Quickly Travel Through Two Heroines, a Mermaid and a Ghost, Pregnant with a Baby

I want to read a book like "The Quick Dressing Guide for Crazy Female Matches". Please go through two heroines quickly. In one chapter, the heroine is a mermaid or a mermaid. Then the other heroine was a human before and turned into a ghost after death. The mermaid is pregnant with the child of a female ghost (I chose the book at random.