That sounds either really weird or kinda interesting. I can’t decide
There isn’t any. That just happens to be where I personally stumbled across the term, specifically reading about the author 吉屋信子
Class S literature is basically early shoujo/the shoujo of its day (early 1900s, but you still get it in literature as late as the 50s), and oriented around romantic friendships or (usually) platonic romance between school girls or women. It was also a type of relationship in real life (and I imagine whether it stayed platonic IRL was much more varied, but it was taboo, and in literature that wouldn’t have passed the censors).
If that might be of interest, there’s a book club. We’ve mostly read the more modern works so far, but we did read one from the 1930s (乙女の港).
