I wish this'd go back to the regular storyline. Not that this side-story isn't readable, but I've seen this "nopan" stuff too many times for it to feel fresh.
10 to 1 it wasn't an orgasm, she just had to piss and he pressed her tummy or something and she peed a bit. You know how these blue-balling authors are. no one orgasms from being pressed up next to someone unless she's got like, persistent genital arousal disorder or something.
Also, why is this an 'extra' and not just part of the main storyline? So they can ignore that any potential plot developed?
Nothing happened. Well except for the part where Kakefu accidentally brings her to orgasm inside a closet, but plot-wise, it's still building up. @Xx_Itz_Jamez_xX he literally made her come in THIS chapter, THIS 4 part omake IS THE DOUJIN!
At this point I get the feeling that the mangaka has told his editor that he can't come up with a new story arc so the editor has told him to just turn some shorts in until he comes up with an idea.