Help? (JP)

I don’t play the jp version but I’m assuming you need to update the game from the App Store.

Hello. I also have this same problem because Fgo isn't available in my country. All you have to do is download the updated Up apk and install. DON'T DELETE. Just download the apk install and open.

As already suggested, update the apk. Some advice from my side would be, install the APK-Pure Appstore on your device. The app will automatically redirect you to this appstore, when you press the button, if you have this app installed.