So I checked out the raw for 28, and it looks like the story is starting to make quite an interesting turn:
Spoiler for AC 28:
The chapter mainly revolves around Nagisa and Karma, who visit Hawaii with Koro-sensei to check out a ninja movie. Also along for the ride is Ritsu, who is now..... an
iphone app: 
After checking out the movie (which reveals another of the teacher's weaknesses), the three (well, more like four) part ways. However, as Koro-sensei leaves, he's watched by two new mystery characters: A creepy-looking bishie kid and some dude in robes:
Spoiler:
Bishie asks if Koro is his
brother.
Robe guy confirms that
yes, he is. Furthermore, starting tomorrow, Bishie will become his
new student...!!!!
So could my prediction about the existence of other super-beings be true after all!?
