One thing that particularly impressed me while I was in Japan, was peeking inside bookshops and library, and see the relatively enormous amount of local books (mostly novels, maybe non-fiction, not to talk about manga and light novels which are a different topic of discussion) published and on sale/for loan. The amount seemed a lot bigger than other comparable markets (such as Italy, France or Spain), and could give the impression it was also larger than a typical US or UK bookshop, yet very few of those novels were translated into English or another European language, and often only the usual names (Murakami, Yoshimoto, etc.).
I have always struggled to know what those books are about, and some hints about the market and the target audience there. I saw for instance many people reading on public transport, but most of the time older people. It is also a topic I have never heard anyone discussing it, as typically when someone talks about Japanese culture always refer to anime, manga and such, and very seldom to films and novels.
https://www.reddit.com/r/japan/comments/11r36mn/japanese_book_tastes_and_market/