@faniki
I doubt he's going there just to help Kilihito, since he doesn't exactly hate the officers of Kyoranki either. I think he just needs to be able to jump in if he feels like it, for whatever reason, say stopping Kaname from becoming a murderer or being killed or similar. He doesn't want to be elsewhere and helpless to change what's already taken place, if worst comes to worst. He isn't quite their breed of hardcore delinquent, and I doubt he wants to see the guys he's had fun with sink deeper into organized crime. If he fails, well... it may be the wake-up call he needs to finally leave delinquency behind him, because he's approaching a crossroad.