Older Hanyuu lets Satoko basically fumble her way through the first few loops, no doubt trying to determine how far the “child of man” can get in trying to overturn Rika’s will to leave Hinamizawa absent any information. The answer: Not that far!
First Satoko interrupts Rika’s dream spiel by leaving the bookstore, explaining how things will turn out, and then making Rika choose, right there and then: St. Lucia, or her. When Rika (notably in the voice of her older self) states that she can’t choose, Satoko jumps in front of a passing truck, painting her best friend’s face with her blood.
Having tried the aggressive route to refusing Rika’s dream, Satoko tries a more preemptive method, getting Rika up at the crack of dawn, showing her the beauty of Hinamizawa in hopes of swaying her. It doesn’t work, so Satoko slits her own throat.
In the classroom, she throws Rika’s exam prep book to the floor, then tears it in two, but Rika won’t stop studying, so Rika takes one of her pencils and stabs herself in the neck. Before long she and Rika are simply yelling at each other while wrestling, and both end up drowning in a canal.
All these loops do is frustrate Satoko. While the deity has been quite entertained, she decides to give Satoko the first key clue: Rika has also been living in loops. Not only that, but far, far moe than Satoko; one hundred years’ worth. Now Satoko understands how uphill her battle truly is, because Rika’s will has been reinforced by a century of failure and despair.
After being given a glimpse of one of Rika’s loops (the one in which Keiichi gets H syndrome and beats everyone to death with a bat), she determines that she needs to fully educate herself in order to have any chance of defeating Rika. That means watching all one hundred years of Rika’s loops…and I thought she detested studying!
Those horrific memories eventually go by and Satoko has seen it all. As with any huge and abrupt passage of time longer than the average human life, it’s hard to fully grasp what Satoko endured, but the her that exists in the “in-between” plane seems more mature, focused, resolved, and most importantly, informed.
When she hears that just before the victory over the Mountain Dogs Rika was at the end of her rope and ready to give up, Satoko realizes it is simply a matter of getting Rika to once again lose the will to go on, only this time make it stick. Like the games in their club, there can only be one winner.
It’s here where I take a step back and somewhat shudder at the notion of Satoko treating Rika like the enemy. Rika’s will is who Rika is, and by trying to destroy it, she’s trying to selfishly craft a new, more malleable Rika to her own specs. Rika, in turn, is trying to mold Satoko to fit her future dreams, and has a head start. It just doesn’t seem either of them love each other as much as they love their own wills. At this point, maybe they just…shouldn’t be friends anymore?!
What is missing is Rika’s awareness that Satoko is looping. So she asks the deity to make it so Rika’s memory persist through the loops, so Satoko is always dealing with the “same” Rika. The only thing Rika won’t remember is the cause of her death prior to Satoko’s, which she also intends to use in the battle of wills she intends to win, no matter the cost.