Very interesting to hear how you perceive this dress. I think in the west dresses with sleeves are more rare than without, especially long sleeves. In Japan and anime you still see sleeved dresses as well as collared dresses. For the west it’s quite old school. Usually people wear dresses only in summer, and casually. So to me it looks like a kind of typical summer dress except with pleats and a collar stuck on, instead of a shirt with the sleeves taken off and a skirts stuck on. Kind of the opposite way you describe it. It’s just interesting how two different people look at the same thing from a different angle.

On the other hand you do seem to have the modern western perception that a collar makes it formal in some sense, and that collars mostly come on shirts. In the past collars were also casual as just wearing a shirt without collar was a big no no. And collared dress were also more of a thing. I completely understand it as in modern days just wearing a collared shirt with the collar open is already formal enough for most work related occasions. In a more classic understanding, the collar on this dress is a casual one because when buttoned up it sits quite low and doesn’t hug the neck closely. Of course in times where cleavage is acceptable in a lot of scenarios, closing the last button at all can be seen as being formal in a sense. I think in an SOL anime or Japanese context, this dress can still be considered casual. Japan still leans more to the classic/conservative side when it comes to clothing.

Here are some Japanese examples from Yuruyuri seiyuus:

• Akari’s seiyuu in pleated dress but with sleeves and without collar: https://lemmy.world/post/24420566
• Sakurako’s seiyuu next to Sakurako in a dress close to Himawari’s but with sleeves again: https://lemmy.world/post/23136792

I also think this dress is very cute! I hardly see collared dress or dresses with pleats “out in the wild” unfortunately. Slice of life anime like Yuruyuri and its fan art is a treasure trove of cute outfits. Namori sensei herself is very good at designing outfits in my opinion. And forgive me for typing lengthy paragraphs about clothes again 🤣.