Merin: Ineoiyagi

A mermaid falls in love with prince Lewen while trying to feed on his heart. She decides to spare him and to die herself. Cursed by another mermaid, the mysterious beauty winds up at Lewen's palace as a human. Unable to speak and express her love for him, she is taken in and renamed Merin by Lewen, who doesn't recognize her. Meanwhile, Lewen's older brother Lewinel, brings home his prospective queen, princess Irena of Ladivita, to restore his impoverished kingdom, Erenbur. But Lewinel, kind and well-mannered, doesn't realize that Lewen is planning malicious intrigues that could destroy everybody's future...

(Source: NETCOMICS)