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Japanese AutoTag is a WordPress plugin which generates tags automatically based on your post title.

For example, if you writes "Ensoku de Fujisan ni nobotta" in Japanese as your post's title, Japanese AutoTag will analyze the Japanese text when saving and set "Ensoku" and "Fujisan" as its tags automatically.

You can configure excluding words so as to prevent specific words from being tagged. If you don't want to set "Fujisan" as a tag automatically, you can add "Fujisan" into the excluding word list.

Note that you have to enter Yahoo! JAPAN application ID to enable this plugin. You can get the ID from the following URL for free: http://e.developer.yahoo.co.jp/webservices/register_application