So, Im looking for stuff where the MC, preferably male, had some crazy thing/s happen in his childhood, and ends up taking on a completely new identity, or developing a secret identity, to get revenge.  I would like for the female lead to be a person who knew the male lead in childhood, but they didn't see each other anymore after said crazy events.  More Specifically: I do not want the female lead to be involved in the Revenge plot IE:  I do not want something where the male lead gets with or gets close to the female lead to get close to her father for revenge or something, in fact, I would prefer if romance didnt have any part in the revenge plot at all, but I do would like there to be romance in it.

The two closest series I can think of off the top of my head similar to this would be (Slight but not really Spoilers Ahead) :  Eun Dae Gu in You're All Surrounded   and  Yong in Iljimae    

Equator Man and Monster are both pretty much that (leads know each other as teens, crazy things happen, guy eventually comes back with a different identity out for blood, haha).  At least as far as I can remember, the female leads aren't that involved with the revenge aspects in either one.

Can't say I can really recommend either of them as fantastic dramas or anything, but they fit.

You must have seen City Hunter, right?

Dramas where the main character takes on a new identity and their romantic interest is only tangentially related to the person they are seeking to take revenge against:

  • Pinocchio (more than one character is seeking some kind of justice / revenge)
  • City Hunter (seconding Knavery's point)
  • The Princess Wei Young (the leads did not know each other in childhood)