I actually used Our Play instead of Gspace since i dunno if its out yet. You just download the Japanese apk of the game and then open OurPlay and inside you can import the japanese apk so it gets google services. Its really easy and you can play it immediately! I hope this helps.

It didn't work:/

i know two ways to download jp server. First one is to download game and copy it to Gspace. Second is to download through Google Play Games on Gspace with Japan VPN server on (you can download Google Play Games by clicking on any reccomended google apps. It will redirect you to play store from where you can download google play games)