WHAT THE FUUUUUUUUUU-
My god, that whole chapter was horribly tense. IDK if I'm just over-invested in the characters at this point, but that was pretty awesome. It's not even over yet (that disembodied arm lmao) but it feels like a lot of story threads all built up to this chapter in a pretty satisfying way. It was interesting to see that glimpse of Taiyou in the beginning; I know he's technically a creeper obsessed with a little kid, but in a lot of ways that's very similar to what Sato herself is doing, and that he's concerned for Shouko makes me wonder if he's not too far gone (i.e, the teacher) and maybe there's some way to make him not-creeper again lmao (also, did I miss something? How did Taiyou know that Shouko was going to Sato's house?)
Regarding the final "twist"; I don't think that's the same apartment Shio and Sato live in together. There seems to be an emphasis on how "this apartment" is "definitely" the place we've seen as Sato's home in previous chapters; Shouko mentions this is where she came and knocked on the door, and Teacher mentions following her back to the building repeatedly but (1) no one ever opened the door when Shouko knocked IIRC, the "someone" she sensed inside may not have been Shio (i.e she didn't knock on the door of the apartment Shio and Sato share) and (2) Teacher's shown watching Sato outside, he may not have followed her in, and therefore would not have seen exactly which apartment she got into.
Either a swap took place at one point (which explains why we haven't really seen Sato's apartment this volume, as another user mentioned; Sato moved Shio out of the apartment listed under her records to another apartment in the same building and had her aunt/whoever the disembodied hand belongs to move in as a precaution) or we've been seeing 2 different apartments all along, the one that's listed under her records (and therefore the one Teacher reported to the police) and whose door Shouko knocked on, and another one with the blood/which Sato and Shio actually live in.