I'm by means no Kurono fan (not a fan of main characters in general) but I have to say that he's had my favorite character arc in just about anything I've read. I thought he was a vile, self-absorbed asshole up until around the time of Izumi's killing spree, but since he's turned into a respectable hero.
The problem is now that Kurono has made this transition I feel his story is over. Now Katou needs to find his killer instinct like Kurono had to find his humanity. I'm sure that's what the second phase is going to be about. Then maybe Sakata will take over. Or maybe Oku will do something even stranger and make Inaba into a respectable character.