Sadamitsu the Destroyer(2001)

Sadamitsu the Destroyer is an anime series following a human warrior thrust into humanity's fight against alien invaders. When an assigned Attendant is wounded during combat, he recruits Sadamitsu to join the battle and prevent the arrival of the Vulture, an ultimate enforcer capable of destroying Earth. But the Vulture has already arrived, and Sadamitsu discovers his own mysterious past holds the key to humanity's survival. As he uncovers buried secrets about his connection to this cosmic threat, Sadamitsu must master his destructive powers to save the world from annihilation.