Overview
The Japanese IME is not ready yet error can occur if the default input method is not set to the Japanese Microsoft IME. In some instances, the issue can occur due to a glitch in the Windows keyboard setting or the language pack itself.
Solution
Add missing files to C:/Windows/IME/IMEJP/DICTS folder from C_WindowsIMEIMEJPDICTS.zip file in the attachments.
Error Code
Japanese IME is not ready yet