I wonder if someone has read this manga. It is one of my favorites, and I consider it a classic. It has action, drama, romance...
Oh, and the main pairing is WELL-DEVELOPED! And the building goes to SOMEWHERE!
Ryo Saeba is a sweeper -a blend of private eye and hitman- that works in the Tokyo's underworld together his partner, Kaori Makimura. Ryo is a real professional, a sharp detective, an excellent sharp-shooter... and a big pervert that only accepts female customers and tries -keyword: tries- to flirt with them... something that does not feel well with his incredibly jealousy, tremendously violent tsundere partner.
The series is very, very, very funny. And the characters are very well developed. Every one of them has a complex background that gives him complexity.
For example, Ryo comes across like a pervert, an idiot and a big child... and then he gets serious, and the contrast is SCARY. And when we found out why he is like that... well, it is pretty sad and you can not help to pity him. And you realize that he acts like a clown because he does not want that Kaori or someone else worries about him.
I recommend give it a try. The stories are good and the art is great. And if you ship RyoxKaori, your ship is safe. Trust me.