That plot twist was pretty cheap in my opinion tbh.
I just want to know about Komachi's intentions n leave this manga for good.
Personally I’ve been suspicious of Komacchi for most of the manga, so I don’t think that’s out of nowhere.
They haven't so much as been foreshadowing or dropping hints as explicitly framing her as a future threat, if this was a tv show there would have been multiple scenes by now of her standing by a window lit from below and smirking evilly while lightning flashes. It's been so obvious that it feels weird to not twist it, because I thought this was supposed to be a mystery series.
It can still be a twist, but just for the main characters and not us. Sometimes that actually works better, like when it was already kind of obvious which Komachi might fall under. It's like how in Invincible, Omni-Man was very obviously evil and always treated as such, but he was still technically a twist villain since the other characters in the show didn't see him coming. It's still risky and the author will need good writing to make it work.