So first off excuse any TL;DR happening here. and i havent read the book nor the article, as far as i recall for the book its largely a philsophical text than a modern historical text on the peroid. (which has its own value anyway) So if you want to research japan (or anything) i would suggest deciding on a peroid first then getting books and the like on the peroid in question written today on it. As far as i know you can find quite a lot of books in any peroid of japanese history in english. (although i presume the further back you go the less you find unless a signficiant event happened that is popular internationally or at least in the english speaking world) I am a tradtionally you can replace book with youtube videos if you want or any medium as long as its relible. I would consider taking the Hagakure as a hisotrical piece comprable to citing "beyond good and evil" as how Germans lived in the peroid or the ideology of germans in the peroid, they do have value as philsophical texts and how that person thought at the time. (And oh god that comparision is more accruate than i realised, Nitzche became more popular after his death, apparntly the Hagakure became more popular after his death as well.) If you want to study philopshy thats fine and the history of japanese philsophy, but its a seperate study to how the people en mass lived in the peroid and that sort. Only advise i have on philsophical texts and memoirs is be skeptical on their historical value. They are great supplimentary texts for the views at the time usually. But the human factor is strong in both, memoirs can be inaccurate pending on when they were written and what they were based off, somones memory can change, phislophical texts are obviously one persons views on how to live. I cant really reccomend any books on Japan though, its not soemthing i have looked that greatly into. My reserch is largely articles and wiki pages on specfic events. (yes i do know to check the sources in wiki) And then everyone has their own opinions on specfic hisotrians anyway and their interpriation on texts and the like. Well, i am beginning to look into the material culture of the IJA in WW2, but thats not really relivent. Hopefully these two links will help for source checking. (i struggled enough to get these, they should cover the basics anyway) Any good detailed historical book should have their sources cited somewhere. That or i am thinking of peer reviwed doccuments. Using Historical Sources Getting started: Reading Primary Sources | Faculty of History, University of Cambridge Anyway, hopefully all that is useful. It is always easier to study one peroid in history then go from there. Or one event that you are intrested in.