Honestly reverse the rolls here, college guy gets under the covers of a high school girl and eats her out in her sleep. The outrage would be insane and no one here would be okay with it. But when it happens to a guy its okay? It doesn’t need to be treated seriously? We haven’t even fully seen Shirasawa’s feelings with everything that happened with Edoka. If the author wants to write a mindless story, more power to her, but please don’t try to get serious. It’ll feel out of place
This chapter felt to me like author was trying for something like "Why the Hell Are You Here, Teacher?" with the whole "she just fall on his dick" shenanigans, but doesn't get why "Sensei" is funny and hilarious ecchi (almost hentai) series, while this is just uncomfortable, even if last two chapters were kinda funny. There is this feeling of dumb, honest earnestness and goodwill in "Nani ... sensei" that is mostly missing here, because characters are too selfish, or because of edgy hentai stuff added for no reason, like her being regularly cummed on by her coworkers out of rape hentai.
I get the feeling those chapters would work better if they were part of a different manga, like about some coomer MC guy who desperately wants to lose his virginity with any hot girl that would let him, but those hot girls keeps molesting him when he can't appreciate it. Something like Larry Laffer maybe.
EDIT: Also author is really showing MC thinking of his partner in crime/freaky sex buddy/totally not girlfriend while being unknowingly sucked by her sister that she's shown to be jealous of? That's just NTR stuff. We have no reason to think he's mindless coomer, given that he's regretting having sex with Edoka since "director shouldn't sleep with his actress" (I know she raped him, but that's not his POV). It's just like messy incestuous love triangle but using "fell onto penis" jokes for some reason. Just like "older sister is so funny ignorant, she didn't realize they came on her" it just doesn't fit the lighthearted horny vibe necessary for those jokes.