Called it! Exactly like I said last chapter!
Also, with this, we can be pretty sure either Miwako or Kawatani (or both) is the BIg Bad, right? Back when they were at the cliff they deduced the culprit must be someone who was at the camp three years ago and was still around last year, narrowing the list to Takeda, Kawatani, Hayashi and Miwako. But it would be absurd - even for this manga - to try and make Takeda the main villain after how much his character changed, and Hayashi is too much of a small-minded thug for the role. It would be like, "he can plot all this without anyone finding out for three years, but then needs to recruit good-looking man just to trick first-years to rape them"? Plus, I doubt either of them fits under the category of people Chizuru trusts.
Also also, once again our protagonists are falling into this habit of forgetting important info while they discuss something else. Do they seriously not remember that the first time she blackmailed the MC into sex, Miwako said she saw Chizuru being cornered by Kajiwara back then? She admitted she was there when Chizuru disappeared! An investigation on that nympho is way overdue!