Connecting Battle Girl high School to Google is a good idea to protect your savedata, which will be stored in Google's servers allowing you to keep it and re-use it every time you re-install the game, even on different devices.

You can do so by going in the title screen and tapping the bottom-left text. Then tap the yellow button with the Google text in it and enter your Google mail and password.

REMEMBER that if you already have a non-Google linked savefile, by using this method you'll create a Google-only savefile, which you can use only if you link the game to Google.

Once you have done that, the title menu will be reloaded and the bottom-left text will disappear.
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