Hello Oliver,
Welcome to Microsoft Community Forum.
As per the description, I understand that you are facing issue with Japanese language pack. I will certainly help you with this issue.
This issue can be caused due to incorrect language pack settings. Let’s work together to get this problem resolved.
I would suggest you to try the following methods:
Method 1:
Follow the steps mentioned below in the Microsoft article.
Change your language or keyboard
http://windows.microsoft.com/en-US/windows-8/using-multiple-languages
Please refer to these following sections and check it helps:
- Set a language as your primary language.
- Add a keyboard layout or input method for a language.
- Change the default keyboard layout or input method.
If the issue still persists, then try method 2.
Method 2:
Try the change the software’s non-Unicode settings:
- **** Press the Windows key + X and click on Control Panel.
- Click on Clock, Language, and Region.
- Click on Region.
- Click on Change keyboards or other input methods of the Regional and Language.
- Click on Administrative tab.
- Click on Change System Locale button under the section of Language for non-Unicode programs.
- Click on the Drop down menu and then select Japanese.
- Restart your computer and check if it helps.
You may also refer to this Microsoft article:
Language packs are available for Windows 8 and for Windows RT
https://support.microsoft.com/kb/2607607
Refer to the section: How to change the display language of pre-installed Windows Store apps.
Hope the information helps. Let us know if you need further assistance with Windows related issues, we’ll be glad to assist you.
Thank you