Casshern Sins

Casshern, a robotic subordinate of Braiking Boss, was said to have been the culprit responsible for assassinating Luna, said to be the savior of humanity when robots had been made self-aware.

In the near future, Casshern emerges out of hiding without his memory. A legend whispers among the robots that killing him will enable the robots to survive a post-apocalyptic Earth.