After fruitlessly prostrating themselves before the bathroom mirrors, Hanako and Kou seek help from Spider-sensei, who directs them to the boundary of the former Second Wonder, Yako, which still exists but is simply no longer under her authority. She leads them to a mirror within her realm (which looks a lot nicer), which leads to the boundary of the Third Wonder.
By the time they arrive, a lot has happened in the Hall of Mirrors. Nene has been put to sleep after trying to stop Tsukasa from forcing Mitsuba to eat the remains of the Third Wonder, which he claims is the only way to keep him from disappearing altogether. Hanako is surprised to see his brother in the boundary, but not as surprised as Kou is to see the friend he thought was gone.
As it turns out, Mitsuba may look, talk, and act very much like the “old” Mitsuba ghost, they’re not the same entity. New Mitsuba is the result of Tsukasa taking the soul, or “reason” he stole from old Mitsuba and placing it in an artificial spirit body constructed from myriad lesser spirits. This new version of Mitsuba becomes the new Third Wonder after eating his predecessor. He also doesn’t seem to remember Kou at all, which is disappointing.
Interestingly, a big battle doesn’t ensue, which surely subverted my expectations. Instead, Mitsuba uses his newfound authority to send Hanako, Nene and Kou back to the living world via mirrors. He may not know Kou, but he knows Nene well enough now to not want harm to befall her, while Tsukasa made a point to be gentle with her earlier. I doubt Hanako can let Mitsuba the Third Wonder stand, but can Kou still find the Mitsuba he knew, or is he truly gone forever?