KI-ME-RA

From ADV:

Vampire vs. vampire, with humanity in the balance! The destinies of two people, along with the fate of the world and its inhabitants, are about to become intertwined.

On a rainy night in California, Osamu encounters a capsule that holds a mysterious green-haired being. He soon finds himself in the middle of a power struggle, as warring factions of vampire aliens descend to Earth. On one side are those who seek to use the recovered alien--Kimera--to repopulate their dying race. On the other side is Kimera's former mate, who wishes to kill him. Will humanity face total destruction, or will Kimera be killed, ultimately saving the world?