Any company or individual in Japan that does business on the Internet is required by Japanese laws to explicitly show basic information about themselves, such as their address, phone number, the name of the highest executive, conditions of their deals, etc. on their website. It is what is officially called "documentation based on specific business transaction law."
The Japanese government has been making it clear that this information be displayed easily visible place from the top page of the website. But in the case of Amazon.co.jp, it is really hard to find it.
First you cannot see it by clicking any of the links on the top page of Amazon.co.jp. So I had to find it by searching the Web on Google, and it looked like it is somewhere under their TOS. So I looked for the link to the Amazon.co.jp TOS, and I found it on the bottom of the top page. It was in very small fonts. After I clicked it, I had to search the entire page for their documentation based on specific business transaction law. I found a link on the left side bar. I clicked it, and at last I was finally able to read their documentation based on specific business transaction law.
This is not the proper way to display documentation based on specific business transaction law at all. Amazon.co.jp must display it where people can find it easily. Normally there is a link to it at the bottom of the top page, and if you click it, you can see it directly. Clearly Amazon.co.jp does not follow the Japanese laws.
It looks to me that Amazon just put it there so that they can show it to anyone who got suspicious about their website and business. I wondered why they want to hide such basic information from Amazon customers. I figure that they do not want any Japanese to know that their company are outside Japan and that there is no one in Japan who would take responsibilities if anything happened.