IMJ Mobile has released Mobile User Book 2010,  a collection of 8 surveys (in Japanese) about the following topics:

• Mobile Video Usage
• New Mobile Services and Technology
• e-Commerce Sites
• iPhone
• Cloud Computing (what is the connection to mobile?)
• Industry's Usage of Mobile Sites
• Usability of Mobile e-mail Magazines
• Flash Mobile Site Usability

The book is available for download as a free pdf, so if you're interested in mobile in Japan, it's worth checking out.