ワンダークラウン/Wander Crown (Mobile): Can't find files anywhere

[Glacier]

Can't find files related to the game. Used both Apk Extractor and Root Browser.

Tried with both an Android phone and an Android emulator.

Note: the game is more than just APK, it downloads the extra files, around 340 MB total.

I'm highly interested in this because the game ends its services late this month.