Blue Triton

Young Kazuya happens upon a baby on the mountainside. This baby - Triton - is no ordinary baby. Triton is the last of his kind, but is raised alongside Kazuya in the city as a human. However, the truth is made known to Triton after he accidentally kills someone.

Triton's clan was in conflict with the Poseidon clan. He must also procreate and increase his kind's size with the other surviving member of his race, a mermaid named Pippy. With the help of dolphins who are allied with the Triton clan, Triton must defeat the children of Poseidon who threaten to harm him and those he loves.

Official English

Volumes 189-192 of the Osamu Tezuka Complete Works