Disallow Japanese Language Comments in Your Blog. 在你的部落格中禁止日文評論
Disallow Japanese Language Comments in Your Blog. (Full Support with AJAX Comments Too!)
Live Demo: Click Here (Try Enter Some Japanese there)
If you have created your own language pack, or have an update of an existing one, you can send gettext PO and MO files to Arefly so that I can bundle it into No Japanese Comments. You can download the latest POT file.