Kaizoku to Ningyo Comic

In a world of barren lands and vast oceans, a rare merman named Hisui is kept by a lord and treated as a valuable possession. Mermaids are traded among aristocrats for large sums, and they usually have white hair that changes color only when they are in water. Hisui has scarlet hair. When the pirate Ikuta steals him away, Hisui gains his freedom, and the two begin a journey together.