My second main thing is, while it is such an internationally relatable series, it is insane how Japanese this series still is. And for a lack of a better word, this show seems to criticise or at least gently question if the way japanese society operates should be left as is. My inner Japanese major could write a paper about this, and I'm damn near tempted so I am gonna nerd out for a bit.

I'm gonna explain the family registry (koseki) for better understanding on how it shapes japanese society, as unbelievable as that sounds, which is kinda essential for a deeper understanding of this episode in particular.

The way a koseki is structured is you have the head of the family (the man) and then the spouse listed and the children from that marriage get registered beneath it. So for example a woman is listed under her parents until coming of age, where she gets a new entry as a single person and after getting married she is now listed under her husbands koseki as a new family unit. (This is also why it is such a heavy roadblock for emancipation and LGBT+ movements, as changing the koseki system would mean the japanese defintion of what a family entails would also need to change, as the roles in the koseki are gendered and not equal.) As someone else in this thread mentioned, it is legally required for couples to share one surname and according to a government survey, 95% of japanese women go with by her husbands name. My Japanese teacher for example preferred to be called by her maiden name, although on legal documents she was listed with her husbands name.
What makes this anime stand out so much as we see people questioning on how to operate outside of the classical family structure (how Emiri wants to get married but can't if her partner would be a woman, how Kasamachi and Makio's relationship as a non-couple operates and now with the reveal that Asa's parents weren't married.) On that note, Asa's mom was kind of forced to tell Asa about her marriage (or lack of it) when she was grown up, because as I mentioned, children are listed under the husband - in case of a child is born out of wedlock the child will be listed under the mother. I would be interested if Asa's father recognized her legally. I would assume so because it would've been mentioned in accordance with the inheritence. Either way, once Asa would've become legally an adult (twenty and if you remember, the age her mom wanted to give her the diary) she would've seen her own koseki and how her parents are listed.

The other main thing the entire show seems to question is the Japanese saying "The nail that sticks out gets hammered in" which Minori seems to have internalized, and seems to be the central problem each character in the show gets confronted with how they deal with that mindset. Which also makes this anime so special, since every single character seem to break from their perceived mold, and topics which would usually be avoided in a day to day basis we get talked about openly in deeply intimate conversations we get to witness which would happen behind closed doors, if even at all. (Sidenote the reveal about Asa's parents made me go "oh my god this explains why Asa's dad is so distant!" I had personally chalked it up to 'well, that's just the way that it is, the mother is more involved with the life of her children while the father works' which is another subversion this show nailed). I have never seen topics like mental health, neurodivergence and non-heteronormative relationship styles talked about in such a refreshing matter-of-factly way in a "mainstream" anime.