intense dramas similar to Innocent Man and Secret where guy falls for girl on whom he wanted to take revenge. Can be any language.
A Love To Kill - Exactly what you're looking for. Guy plots revenge on the girl.

Time Between Dog And Wolf- This is not exactly what you asked for. It's similar, though. I can't go into detail without giving away an important part of the story.
Green Rose, Resurrection and Five Fingers seem to fit the category so well.
I like this theme too....any more suggestions?? I have seen most of the ones mentioned....
Hi guys, I have the same problem.Can not find a revenge-romance drama that I did not seen. Very good drama in this category -a little old though- with a very good acting and a major twist at the end is Japanese drama "HUNDRED MILLION STARS FROM THE SKY" . Plot is : The down-and-out detective Kanzo Dojima (Sanma Akashiya) is thinking about hanging up his job. A mysterious man named Ryo Katase (Takuya Kimura). No one seems to know what’s going on in the heart of this lonely guy, what he believes in, what he really loves. Then these two men meet by chance one day. The story takes an unexpected turn of events concerning a murder case. Maybe the two of them should never have met. And then there’s Kanzo’s sister Yuko (Eri Fukatsu). What will the relationship between her and Ryo be like?
Try these: City Hunter A Love to Kill Bad Guy
Giant - guy falls for girl also another girl falls for a guy...2 couples in revenge-romance :D
thank you folks for your suggestions.. but i have already watched A Love to Kill Time between Dog and Wolf Greenrose A Million Stars from the Sky (although it has a different and complex theme and I liked it.. and Takuya Kimura one of my favorites) City Hunter Bad Guy(Innocent Man) However, I will try Resurrection, Five Fingers and Giant Let me know if any more suggestions..
For those who haven't seen it I would highly recommend "Sealed With A Kiss"