Utakata no Koe wo Kiite

For years, Aito thought he was just a normal kid—until the day he fell in love with a boy at school. Suddenly, a flood of memories come rushing back, reminding him of his first life as the tragic little mermaid who risked everything for her prince, only to fade away into foam. But memories aren't all that Aito inherits, as a mysterious power wrenches away his ability to speak or stand before his crush without agonizing pain. Ever since, Aito has sworn off love in self-defense, but a fateful encounter with his charming college classmate Toru might just irrevocably shake up his world...

(Source: Kodansha USA)