With its major story arc completed and the Flask Plan defeated, but with no time to move into its next major story, Medaka Box Abnormal doesn't so much break the fourth wall as smash it to pieces with an almighty hammer in the name of explaining what follows in its final episode - a side-story featuring the newly introduced Misogi Kumagawa before his transfer to Sandbox Academy.
Thus, after that odd introduction by Najimi Ajimu, we join Fishtank school's student council president as he looks to help out his council colleague Saki Sukinasaki after an abrupt colour to the change of her hair causes her untold hassles in her school life. Given that she didn't perform this colour change herself, it doesn't take long to find the true culprit - Fude Ezumachi, a loner with the ability to control colour and bend it to its will, and a boy with a bit of a grudge towards Kumagawa after his heavy-handed removal of the previous student council president.
The lines are drawn henceforth, as Fude looks to make Kumagawa suffer using his ability while Kumagawa himself looks to use his All Fiction to win the day in the name of.... well, protecting the colour of girl's panties for the most part. The whole conflict pans out with Kumagawa also looking for someone with the potential to defeat Ajimu (aka Anshin'in), but it seems that when push comes to shove little can stand in the way of All Fiction, especially when this ability to undo absolutely anything even extends to removing entire colours from the world.
All in all, I'm a little torn about this finale to Abnormal - in some senses I appreciate the way in which it's introduced Kumagawa into the show, and as a stand-alone episode is arguably did a better job of presenting itself for the small screen than most of the series proper from a viewpoint of "this wouldn't have worked as well in manga form". On the other hand, I'm not sure quite how well this introduction of important characters sits against doing it "by the book" (the manga book, in this case), although time will tell on that note - assuming we ever get a third series, that is, and that prospect must surely be up in the air after a second season that has been an improvement over the first, yet still lacklustre in the grand scheme of things thanks to a lack of real energy or flamboyance to its adaptation of the original manga. As someone who tends to enjoy watching anime more than reading manga even when the former is based upon the latter, it's rare for me to hold a definitive preference towards the written original material, but that's exactly what Medaka Box has succeeded in doing so far, which sadly is far from a glowing reference for what GAINAX have done here.