A few years ago I was inspired to consider a setting and story line based on medieval Japanese society. So I initiated research into Japanese history, religions, architecture, etc. All part of the world-building process. Plus, while conducting research, I get ideas for story elements.
I purchased Across the Nightingale Floor some time ago without realizing that it was the first book in the Tale of the Otori series by Lian Hearn. I confess that I haven't read it yet. But I inadvertently learned that Heaven's Net is Wide is a prequel to the series, so I purchased a paperback copy for research purposes.
I've done this before. I use published historical fiction as a resource for period detail. I don't concern myself with accuracy since I intend to build my own world for my YA fiction anyway. But authors of historical fiction have likely done way more research into their setting than ever appears in the published novel. So I confess -- I take advantage of their hard work.
For anyone creating a fantasy setting for their novel, I highly recommend Patricia C. Wrede's list of questions for world building. Located at the Science Fiction & Fantasy Writers of America web site, Ms. Wrede's questions cover all the bases and really make the writer stop and think about the world that he or she is creating. I've made my own world-building template in MS Word based on her questions and fill it in as I conduct research or get "brilliant" ideas for the world of my creation.
I've started buying composition books on sale at the big box office supply stores (back-to-school sales are great for writers!) and compile my research notes and ideas in comp books dedicated to specific stories. I like the "quad. ruled" books because I write small and the narrow lines suit my scribbles. I play with character names and story ideas in the comp books. I record my notes from library books in them, and even notes from my own books so all the relevant information is collected in one place. And I highlight the things that I think most relevant to my story.
My idea for a Japanese-inspired YA fantasy is beyond my current writing capabilities, but I continue to jot down my thoughts and record my research. Currently I'm skimming through Heaven's Net is Wide and underlining in pencil details that I will transfer to the second comp book for my fantasy setting.
The details I collect include customs, social norms, costumes, household accoutrements, methods of travel, etc. The sorts of things suggested by Ms. Wrede's world building questions.
So...forgive me, I may have sinned. I'm presently taking advantage of Lian Hearn's extensive knowledge of and research into medieval Japan. The Tales of the Otori appear to adhere more closely to historical Japan than I intend to do in my story. But Ms. Hearn has captured the nuances of a period and society. I hope to learn from her as I piggy-back on her research for the world I hope to create.