Feels like the author got the story axed at the 8th or 9th chapter.
Suddendly changing her from a spider youkai to a energy based alien, making that she had got everyone in the school under her control aside 4 people, for literally no reason as she didn't use them, making that MC had encountered the girl she possessed and that girl had some feeling for MC but then...it just stops there.
She left, unclear if the planet or just back to where the girl lives.
Is pretty bad as is clear with the exorcist kid that she was planned to be a japanese youkai and the whole thing was axed.
Even MC remembering to having seen her in the past and running to the location, should have been a classical cliche with the 2 meeting again but the mangaka wasn't given time.
This author makes unique stories, but this trash ending is clearly a axe.