User blog comment:Halo1081/Chapter 128 and forward/@comment-151.229.112.223-20150221090107/@comment-25993554-20150222025209

Well, there seems to be some kind of structure there. Maybe you're right.

Given that Kayano called Nagisa there, she (or maybe they) must need him there, for reasons unknown.

Unless, he was only needed there to clear any suspicion, so Kayano could take Korosensei off guard.