Japanese text in Windows game won't display correctly
I did some digging and it turns out you ran into the same problem that is described in this question.
The solution is quite simple:
The game doesn't support Unicode and thus you have to change the language used for programs that don't support it manually in Windows. By default it is set to the OS language.
To change it in Windows 10, do the following:
Click the language symbol in the bottom right of the task bar next to the time and select "language preferences".
In the opening window, select "Additional date, time and regional settings" at the bottom.
Select "Region".
In the "Region" window select "Administrative" and then "change system locale" for non-unicode programs to Japanese.
You will need to restart the computer and then the symbols should show correctly. I tested this with Action Mogura and it solved the problem. It is also not necessary to install the fonts from the game folder, so you can uninstall them if you like.
Changing your locale works, but that will make a lot of other things difficult to do, and essentially makes Windows tell your entire computer that it's Japanese.
An alternate solution would be to get Locale Emulator or the like. Then, you run the game under this program, and it simulates the locale change.