5000 years ago, the Triton Family was living peacefully in Atlantis until the Poseidon Family destroyed them all out of jealousy for their successes. The race of merman was annihilated leaving Triton, the last survivor of his kind. Ruka took the orphaned Triton to Japan in order to protect him from his enemies. (Source: Wikipedia)

Umi no Triton was published in English as Triton of the Sea in two omnibus volumes by Digital Manga Publishing from October 2 to November 26, 2013.