I got myself JP version just for this. [D4DJ Groovy Mix] 

No you don't.

It was a reroll account :')

If you mean the app, I get it from qooapp. If you're an android user, download qooapp first, and then the d4dj jp on qooapp. Unless if you're an ios user, I think you need a Japan Apple account. If you mean the account, you can search d4dj jp reroll and see any online shop that sells them. (I got mine on shopee) I hope this helps!