No more than 2 books can be recommended per commentator. If this rule is violated I will consider reading only the first 2 recommended.
@EnopoletusHarding For less math, Thinking Physics. For math, How to Solve It. If you already know math (specifically: differential geometry), Spivak's Physics for Mathematicians (which I discovered through MathOverflow).
If you're looking for textbook-style recommendations, try looking at [reference-request] tags on StackExchange. For example, Econ StackExchange, Physics StackExchange.
Also check out LessWrong's Best Textbooks / Best Tacit Knowledge Videos on Every Subject, and John Wentworth's technical AI alignment study guide!
@EnopoletusHarding Can you give us more details on what subjects you're interested in? All of history, or only certain eras?
@EnopoletusHarding There is a manga from the 70s called Onward to Our Noble Deaths which was written by an actual veteran of the Imperial Japanese Army. It's a grim anti-war story inspired by his experiences, although it's not strictly autobiographical. Even if you don't care for comics, it's a pretty fascinating document.
My other recommendation is We Meant Well: How I Helped Lose the Battle for the Hearts and Minds of the Iraqi People. It's the work of a state department employee who was involved in trying to rebuild Iraq, and he talks about how almost everything they tried ended up being a near-complete waste of time and money (especially money).
@EnopoletusHarding Patrick McKenzie (patio11) recommends Making Common Sense of Japan first, and then An Introduction To Japanese Society if you want more breadth and depth.
patio11's discussion (of Japan, not of books)