Who stuffed a GantZ up his butt? Seriously, if he wants to join Izumi just for the heck of it, fine...but why does he bear strong animosity towards Kurono?
"He's just a normal brat!"
"I'll never accept him!
"Finish him off!"
What the heck? It's not because I hate him (because I do) but his hatred for Kurono makes no sense.
Izumi, on the other hand, makes perfect sense. He's the complete opposite of Kurono, his negative. He was the man who had gotten 100 points and yet a newbie like Kurono can outmatch him. That easily sets him up as Kurono's counterpart with valid, understandable reason...
Inaba just seems like the guy no one gives a crap about, that jumps around shouting "Hey! Hey! look at me! Please, pay attention to me or I'll die of lack of attention!"