Satoko did not predict her uncle would be reformed to the degree he was as an effect of her loops, but she’ll still use him “to his utmost potential” in her overarching goal to keep Rika right where she is: in the “birdcage”. One of the key figures in assuring that outcome is Takano Miyo.
Miyo is taken out into the rainy woods by members of the Mountain Dogs. where she is told the operation has failed and all physical evidence related to it will be destroyed, including her beloved scrapbook. She’s also given a gun with one bullet to blow her own brains out, or it will be done for her.
Miyo wakes up in her office, clearly having experienced an alternate fragment and, like Teppei, considered it more than a dream, but a warning of what will come if she continues on her set path. The orders to get rid of her in that fragment come down from Nomura, a woman in Tokyo Miyo trusted. She gets a call from Nomura shortly after waking up.
As such, the possible events she just “dreamt” are foremost on her mind when Nomura informs her of what must happen if she fails her operation, which involves infecting Tomitake with Hinamizawa Syndrome. Miyo’s dear departed grandfather’s research will be dismissed as “fanciful nonsense” and he’ll be a laughingstock.
Miyo recalls when she was much younger and served as her gramps’ assistant, only for a bunch of old guys to come in, listen to his research, and dismiss it as…fanciful nonsense. Never the less, Miyo would grow up, go into medicine, and carry on her grandfather’s life’s work. In a meta moment, one of the old dudes says he’ll recommend a publisher for her gramps, as his research could make for some entertaining fiction.
Before Satoko comes in for a routine checkup and tests, Miyo has the sudden urge to take her scrapbook out of the safe, no doubt fueled by her “dream” about it and her ending up in the mud. In it she discovers a letter to her from her gramps, imploring her to stop pursuing the research and go life a “wonderful life”.
During their tests, Miyo tells Satoko how she’s considering quitting the Irie Clinic, considering that if she stays she’ll eventually be discarded like “ingredients in soup stock”. During Rika’s dance, Satoko follows Tomitake and Miyo to Oyashiro’s storeroom, though only Miyo goes inside.
Back in the ethereal plane, Eua notes that Satoko is working towards a world where the rules of Rika’s tragedy no longer exist. Satoko intends to take on the mantle of Oyashiro-sama and punish Rika for longing to leave Hinamizawa with the curse of another virtually endless cycle of tragedy, in which Rika will “learn” that her proper place is Hinamizawa, by Satoko’s side.
When Tomitake arrives for his “prophylactic”, Miyo takes out a vial of H173, but decides not to go forward with injecting him, thus scrapping the operation on her own terms. Without Tomitake succumbing to the syndrome, the rest of the “final operation” cannot happen. Satoko uses Miyo’s reluctance in this fragment, borne from previous fragments, to steal a vial of H173 for herself.
Eua asks Satoko if she’ll really feel no guilt or remorse for resorting to such methods to achieve victory, and Satoko, made both wise and weary by her decades of looping, says none at all. After all, the world she’s working toward, in which she and Rika are together, will be devoid of tragedy, and that will be the only world that really matters.
With that final declaration, delivered with red eyes and all the fervor of a girl obsessed, the story of GOU is concluded, and the story of SOTSU is announced as a continuation of Satoko’s quest. Rika has been ready to move on with her life for some time now, but Satoko isn’t ready to let her.
She can’t accept a future in which the two of them simply drift apart, as friends sometimes naturally do. For all the pain and suffering her plan has caused and will surely continue to cause, I can’t help but pity Satoko as much as I do Rika and the other victims, and I’ll be back to see how it all turns out.