Give the raws a 'like.'
Hardly know where to begin besides whoa.
This chapter starts clouded by foreknowledge that Aoyama was taken advantage of. The flashback is presented in quick snapshots, jumping from scene to scene without transition. These snapshots could all be sweeter in another context (and it lends to the surreal imagery later) but they have a deeper purpose: these are the moments Aoyama smoldered over for 6 years. She flips through them like old photographs as the rest fades away, an idyllic trauma she can't move past. It wasn't meeting Yurika that hurt her, it was how casually she was cut off after being used.
Aoyama's been trapped in the memory of something she couldn't emotionally grasp. She stuck to the library when it must remind her of Yurika every day. She cut her hair, baring her "mean look" to the world because she must not care if she scares anyone off anymore. She's not reserving it for Yurika either. But maybe she's feeding off the confidence Yurika's compliment gave her. The one thing she knows for real is Yurika broke the rules out of desire for her. She checks her stowed letter with bitter satisfaction when no one took it. The letter existed as a reminder of her loneliness and a pathetic little rebellion against Yurika's words. So long as it remains they still had that thread binding them. The thread Aoyama now tears after Yurika's return.
And here we have the generational gap. When Aoyama says, "There's no one else for me," there's a double meaning. Both that she never wanted anyone else and that Class S is extinct. Aoyama is the last dinosaur, forced into perpetuating a system that forgot its purpose beyond putting tradition on a pedestal. A system Yurika seemingly* couldn't care less about but uses in such a mechanical way to detach herself from her little sister, a convenient excuse to abandon Aoyama and guilt her into growing up past this "childish" love. Packaging the disgusting bits of Class S into the hypocritical veneer of honoring its legacy.
As the in-setting rules for soeurship are codified, it's fascinating how only Kasumi and Haruyo have done it to tradition. Yurika circumvented the system to pick her partner (and while she called her by a nickname, Aoyama only called Yurika 'Senpai'). Yamabe and Mia were only glanced by the letters and never participated in roleplay. Sayori and Mizuki engaged with it as a distraction but their relationship clearly enveloped it rather than being defined by it.
That isn't to say none of them live up to Class S - this entire manga is a love letter to the old genre and a bridge into the new. Each arc could serve as a classic Class S story that twists into the modern standards of yuri, for all that means.
Everything Kasumi and Haruyo have done is under the umbrella of Class S. They met through anonymous letters; Kasumi fits the stereotypical little sister to a T (despite her fears otherwise) and Haruyo does her best to embody an Onee-sama. You could describe them as the purest and healthiest couple, without the major upheavals or gaps others suffered. Though they've gone through pain and bitterness with more to surely come, it's through the lens of Class S they take comfort in each other. Their roleplay allowing them to open up difficult topics and recognize their truer or idealized selves.
It's ultimately a positive influence on their romance, on the romances of the 2 settled pairs too. If there's only one theme to this manga it's that. Class S was born from a painful time in history, but that pain paved the way to happiness. Yuri is the celebration of what Class S laid the groundwork for. By paying respects you take the good with the bad, exploring degrees of bittersweet to downright toxic before ultimately finding that brighter path together. Breathing new life into the old genre.
Somehow I expect Aoyama and Yurika to find some happy ending too. Igarashi is excited to show off chapter 18. And it can't escape notice this arc's flower is the most significant of all: yuri. Whatever Igarashi means by that I'll hold judgment for now. The same goes for Yurika. I can only say Yurika clearly does value Hanamonogatari, if not the trappings of Class S. She became the classic literature teacher for a reason. And returned to this school for a reason too.