Should you have installed this JP version at some point, then uninstalled and moved on to English ver., note that the Steam client (is instructed to) only uninstall the launch files; it does not include its application data, aka the stuff it downloaded in-game (7.45GB as of my last update).

You can check it on this location:

Found this out during my diskspace spring cleaning & stuff.
I can imagine it'd be the same for the English ver.