Thanks for the help. I got that DMM game store app butnow, where I'm supposed to found FKG app? I just got a link to the FKG site. The GooglePlay link at the bottom bring me back to GooglePlay with the same unavailable issue, AppStore don't work because I'm not on Apple and DMM link lead me to the PC version.
I'm a bit lost in all thoses japanese moon-runes...
Sorry for being a huge newbie with all this stuff.