So basically Izumi represents chaos ... And so he and the gang rapists decided to join forces and try and murder everyone else ...
By the way, why didn't Kei die for explaining all of that, or is it because she already knows (well could potentially know had she checked her camera)
Also the reason that Tae can see Kei is because he is on the frequency of the real world ... though not sure why they can all see him but w/e.