Yoon Suin is a fantastic toolkit if you want D&D adventures with a more asiatic/eastern flavour. It's a lovely pink covered landscape book.
Or it was. Lulu no longer do landscape so you can't get it in print, unless you buy the PDF and use a printshop like doxdirect.
There may be a revised version coming, but it it goes portrait, it'll lose some of that uniqueness.
PDF is here: https://www.drivethrurpg.com/product/144820/YoonSuin or from the creator's site here: https://noisms-games.squarespace.com