First things first, I don’t know any Japanese. Neither speaking nor reading/writing. I have absolutely no understanding of the language. Still, I own a few Japanese books (with some more on their way to me) because they are guide books of my favourite 3DS games.
Books like the one below are very detailed, very well made and can even help you if you have trouble with the language, because they clearly map the dungeons and provide the most important monster/enemy stats in Roman letters and Arabic numerals.
The book for Animal Crossing: Happy Home Designer is fine as well. With 700+ pages it not only lists all the Animal Crossing customers but also all the available items as well as their different colouring/modification options. What a great resource!
The only downside of those books: They don’t come cheap and importing them from Japan doesn’t make them any less expensive. But for some games there isn’t any alternative if you don’t want to browse online all the time.