And Aizawa didn't notice the other spirits in the shed, nor the MEG who may or may be not inside Michi? Could it be that Aizawa is a ghost who cannot perceive other ghosts?
It wouldn't shock me if it has to do with her nature. It's been made a point several times Aizawa is rapidly evolving and different from normal ghosts, and even if Michi isn't experienced enough to make that call it would still be an odd move narratively to contradict that. Either Aizawa can't see ghosts herself or somehow drives them off through sheer bubbly gay energy. It is weird that action scene just dissolves the moment she shows up. Maybe we'll get some kind of explanation next time.
It will probably be brushed off with something like “Kasumi-chan was too tired so she fell unconscious on top of Michi while trying to hug her”. And Michi herself will believe that and be oblivious about the Yuri ghost.
Until something like this happens a second time, maybe with another person, and/or Aizawa’s ghost herself goes straight for the mouth when “touching” her (despite not being able to feel anything, that’s as good as it gets for a sign)
I don't know if density can survive a situation this far gone. Aizawa knows what she did, Senpai might realize her girlfriend(?) got possessed and at least knows there's some horny ghost chasing this girl around, and Michi will notice Aizawa freaking out around Senpai. It all depends on if Senpai levels with Michi about her haunting but I don't see much reason to prolong it with the mark being a serious issue. The story easily has enough legs at this point to grow beyond Michi ignoring Aizawa.
Plus I really want to see that relationship triangle of Senpai forgiving Michi and giving her some guidance, Michi still being terrified of Senpai, and Senpai losing it at the dumb ghost that keeps running to Michi for safety.
Also I'm not sure how much stock to put in this, but Aizawa is the cover manga of next month's issue of Comic Valkyrie so it might be a big deal chapter.
Edit: actually, I find it super strange how, when Michi first sees that ghost waiting in the storage shed, her response is to make an excuse to get Kasumi away and then go in alone. Why did she do that?
She did mention she had a weird feeling about this one and probably figured she's better off alone since she can see and avoid it just in case. It'd be hard to talk Kasumi through that.
Michi already has a case of a ghost "attacking" her without acknowledging it, Aizawa herself, but she still naively assumes the situation won't get too bad so long as she ignores them. Which is why she thought she tripped instead of getting grabbed. Though I'm speculating that's not because this ghost is particularly unique but because of the mark's influence.
Tangentially, I like the little theme of protectiveness in this chapter. Aizawa helping Michi and crying a little when she knows she's safe, Michi going out of her way to keep Kasumi away from the slightest chance of trouble, Reona immediately getting serious when Kasumi's hurting and taking charge with Michi, and Senpai hastily jumping to conclusions in Kasumi's defense.