STEP 1.) Right-click any open space on the taskbar. Point to Toolbars, then choose Language Bar.
STEP 2.) Right-click on the EN icon (or whatever is there) and choose Settings.
STEP 3.) This dialogue box will pop-up. Choose Add.
STEP 4.) Choose Japanese from the drop-down menu and click OK.
STEP 5.) Click "Key Setting"
That opens up Advanced Key Settings. Look in the Action part you'll see list of languages saying "Switch to ...." Here is where you assign a *specific* command to instantly switch to the languages you want.
STEP 6.) Click on "Switch to Japanese ...." to select