I remember reading a book in my late middle school or ealry high school years but I can’t remember the name.If I remember correctly it was post-apocolyptic where humanity lived in the mountains and the oceans. The main character comes from the ocean. Their sister takes a hot pill thing that makes them a mermaid like thing? But the MC takes one cold so the transformation takes a long time. Could anyone help find this book series?
by Used-Print7326