Amazon.com operates a very large online store in Japan as well, featuring tens of thousands of Japan-specific items not listed in their US catalog. But, you can visit the Japanese website from your own computer, and even if you can't read all of the Japanese there is now an "English" button that allows you to access the basic functions (but only the basics) of the store in English.
Since even if you're using Amazon Japan in English, Japanese kanji still sometimes appear, I highly recommend using Firefox's rikaichan extension to give you point and click definitions of any unknown kanji.
Also, Amazon Japan accepts US credit cards and will ship to the United States. Most orders can be shipped for around $15, which is an excellent price and probably the best deal you can find online. Plus, Amazon is a major company with excellent customer service, so you don't have to worry about getting ripped off.
Throughout this site I have linked to Amazon Japan's products whenever possible to highlight the books and other products I am discussing. I receive a small commission from each successful sale made after someone clicks the link from my website, so if you appreciate the information on this site, and you are going to make a purchase from Amazon Japan, please use the links on my site first. I appreciate your support, and it helps insure I can continue to keep this site running and updated.
If you're searching for general Amazon Japan merchandise, please use the box below, as it will generate a small amount of money for me (at no additional cost to you!):