The only thing that might save this manga now is if mima is the vengeful spirit.
I was really hyped of having a Satori manga, and while I know she has a standoffish personality, they could have done more than make her appear fucking useless by always being late to the spirit's mischief, and then have these bare-bones interactions with the rest of the cast. Satori has been in the Chireiden for a long time now, she's a fish out of water, she's a perfect POV character for Gensokyo's overground shenanigans, and it's vastly underused.
Furthermore, the story's plot points feel tedious by now. It almost feels like they're not going to reveal anything substantial about the spirit until the end, and just chasing the spirit around is not amusing by itself.
I know ZUN can write compelling narratives, but the writting in this just falls flat.
The art is quite bad, too, I'd rather not grill it much on that though. (and others have already mentioned it as well)