Set in a universe where the Earth has been taken over by robotic immortals. Most humans have transformed themselves into robots to join their captors, who are now concentrating on capturing the Sea of Stars. However, one man, Warrius Zero, has refused to give up his humanity even though he has lost his family. Now in the employ of the Earth's captors, Zero finds himself on a extraordinary mission. Long numbed to any feeling of remorse for betraying both himself and humanity, Zero's emotions are re-awakened when he is assigned by his masters to hunt down a legendary space pirate known as Captain Harlock, a man who was once his best friend.