I’ve contributed 3 articles to a recent Japanese publication (プロが選ぶ WordPress 優良プラグイン事典) on WordPress Plugins.
It lists useful Plugins in 7 different categories such as image, mobile, social, editor helper, etc. There are surprising many WordPress books in Japan but I often hear from readers of them (especially from beginners) that they wish the Plugins recommendation section was longer. Since majorities of Plugins only have their official documentation in English and many Plugins are not (yet) localized, Japanese users often get lost in choosing safe and reliable ones that match their needs.
The team of 17 coauthors teamed up because of a WordPress news/tutorial blog WP-D, which launched with Hajime’s lead after WordVolcano Kagoshima event in July 2012. It was nice to work with other WordPress enthusiasts for this book.
Here are some shots of pages I wrote:
Jetpack by WordPress.com
WP Multibyte Patch
This book is available in Japanese Amazon.co.jp. There is a Kindle edition as well (you will need an Amazon.co.jp account instead of Amazon.com).