"Enemies become friends" manga

[kujika]

Hello =)

I'm looking for a manga that has the following topic included (doesn't have to be the main focus though).

"Enemies become Friends"

I prefer shounen/seinen/josei to shoujo (high school intrigues), but feel free to recommend me anything ^.^

Thanks a lot!

[DoorKnob22]

Superior should be up your alley though I'm not finished it yet so I'm not sure if they'll end up killing each other or becoming friends yet.

http://www.mangaupdates.com/series.html?id=64917

Is right up your alley, though they start "dating".

You might also like Code Breaker.