As part of of the "team UX" at work we're doing a bookclub to make sure we all have good foundations in UX before making it a company offering. We're starting with two books: The Design of Everyday Things by Don Norman, and UXデザインの教科書 (The UX Design Textbook) by Masaya Andou.
While I work reading and writing Japanese all day (when I'm not slinging code), I haven't read a book in Japanese in ages. This is mostly because what I'm interested in ( technology, the web etc...) is usually written about in English well before Japanese. And since I can read English natively, it's natural for me to pick those books.
Starting to read UXデザインの教科書 yesterday and the first thing that hit me is how much my Japanese has improved in the last 4 years. I used to struggle reading texts written for native-speakers as I had large gaps in my kanji recognition abilities. Gaps still exist. But now they're small enough that reading a single page doesn't take 20 minutes as I look up every 5th word. Only taken me...20 years(!) to come the far.