Board Thread:General Discussion/@comment-107.219.185.91-20140105042639/@comment-72.10.223.93-20140219011606

I think it's likely that Otonashi wandered between the worlds for a while; the first chapter of Angel Beats! Heaven's Door shows Hinata talking to someone who looks like Otonashi (although we never see his face).

Yuri said that there were ways to tell humans apart from NPCs. I assume that's how they figured it out that Yui was actually human. If you ask that, then how do you know that any of the other members were actually human?