This Japanese bookstore chain is known in New York for their gigantic manga section. They have three stores in Bangkok; the one in Isetan at Central World is the heaviest on Japanese titles.
The Siam Paragon branch doesn’t carry much manga, but it is the most spacious. Most of what’s here is in English and Thai and there is a very large language learning section.
Stuff you’ll have a hard time getting outside of Bangkok that you can get at any Kinokuniya here include: Thai cookbooks in English; books on Thai and Southeast Asian art and culture in English; children’s books in Thai – they’re beautiful and a great way for kids and adults to start learning the language. There are three locations, including Siam Paragon, Isetan at Central World, and EmQuartier Shopping Complex.