Uchuu no Kishi Tekkaman Blade

Tekkaman Blade takes place in the year 2300 AD. On a certain moment, the Radam attack earth. A few months after the beginning of the invasion, a tekkaman appears, he calls himself Blade and with the help of the Space Knights, Blade starts to fight the radam. But there are a few things that Blade isn't telling about his past.

(Source: Anime News Network)