Yuki (and any others looking for alternate language books)....

...I used to live in the San Francisco Bay Area (East Bay)...each of the major cities had their own local districts where people of a particular foreign nation (as well as Americans - natch) would congregate / live / and do business - San Francisco CA has their Chinatown, Oakland CA has a (small) Koreatown, Los Angeles has a very large Japantown....I've seen a couple of 'mom & pop' book stores in SF's Chinatown so I would like to think the same could be found at the other locations. 

You might try a search for book stores in a major city by searching like: Japantown Los Angeles, Japanese books - to get a few hits and 'see' if there is a website or contact info. Then you can either send email or phone, and ask if they have what you may be looking for - or if they can get you what you are looking for...like most any other bookstore - if they don't have it then they can probably get it for you by ordering it (either from the home country, or thru another similar bookstore (i.e. their connections) - helps if you have a title / author and esp an ISBN to give them. 

Same for some Swap Shops (Big time permanent Flea Markets) - some of the big cities have huge flea malls nearby that have permanent sellers who 'specialize' in specific items such as DVD's or books (or knives, depression era glass, whisky bottles, etc). Not sure how you would do a search for them, but seems like everyone has a web page of Facebook link - worth a shot!

Good luck! 

Danny N (Alameda) - Havelock NC (was Alameda CA - East Bay)