I know if you go to a country and use wifi over there or a phone card and access your google play app it will ask to change stores I've done this firsthand when I went to America and It changed from the Au store to the US and I got to download with no hassle tamagotchi life and tap and hatch.
So we just need someone to go to Japan and get it or there are apps that can change the store setting.
in google play you just need to log into your google wallet on the computer and go to address's and change your address to a Japanese one it doesn't have to be a home address just take any from google I've done this several times and I've also changed my itunes to japanese and back but as long as the app doesn't cost anything because then you need a Japanese bank