How to change the language used on Mac App Store? I used my old Mac which showed me English when I browsed through Mac App Store. However, after I purchased my new Mac and ported all the data using Time Machine, the Mac App Store suddenly shows me Japanese for some reasons.

I use English in OS Settings and everything works fine except the Mac App Store. I live in Japan, which is likely the possible reason it shows me Japanese.

Why do Apple use the different language only on the Mac App Store? And how can I resolve the issue?
After I fought with the issue for a few hours, I found the solution.


Open Mac App Store and log out of the account.
Restart your Mac.
Log in to the account again. 


You might have to log out of the account first before restarting, for your information.



UPDATE

However, while the solution here worked in my OS X, it's not the case in iOS. In my iPhone, which is set to Italian, the iOS App Store displays English, while my iPad that uses Spanish displays Japanese. This is so frustrating bug in Apple; I don't get to how this can be resolved...