You need a Japanese Play Store account if you want to play the game right now, simply installing an APK won't work. A global, English version of the game was mentioned to be set to release sometime during Spring of this year but there hasn't been any notice on that in months.
@@rokkudayo I mean RWBY is more popular than Black Rock Shooter nowadays but Black Rock Shooter is more respected nowadays in terms of its storytelling than RWBY is. So make of that what you will lol