From killers to lovers

This is a action-romance-mystery-comedy story about 3 man who first only lived to kill and have fun until they found them.The story is this :
KJK,JCW,KTH mafia gang members who do different assignments for the gang till they found someone who cant defeat.

The main characters:Kim Jongkook the powerhouse and the leader of MN(later the reason why is called like that) gang,intelligent and quick-witted.Nickname:Commander,KJK
Ji Chang Wook the man with a black belt in taekwondo an ace in every field,cold-blooded when it come the the job.JCW Nickname:The executioner
Kim Taehyung the youngest one,hot and funny guy,,known for his flirting skills and very smart.Nickname:Cassanova,V

The other characters will be introduced in progress everything that happens is a decisive thing in the future
even the smallest detail is a hint.

So let see if you can see through this.

* is Jongkook
~Is Ji Changwook
<Is V