After bring left for dead, an immortal fighter comes out of retirement starts a underground fighting promotion and goes after those who killed him with his fists.

He is a cyborg.

"After he's betrayed and beaten by a jealous rival at his martial arts academy, a fighting savant dons a mask and enters the emperors fighting tournament in order to defeat the student who left him for dead."

I revised it.

Echoing Richiev sentiments, the protagonist does sound like bad guy. There are a couple of typos as well that make for a less than smooth read.

As written the protagonist sounds like the bad guy.

You might need to explain why even though he is immortal, he goes after unsuspecting women. Shouldn't he go after those who left him for dead instead?