I'm very thankful for your information, but can I ask for one last help? Can you tell me how to back up a save in Android? Do i need to download some applications? And what do I do after I already back up the file?
Open your file manager, whatever that may be called on your device, then navigate to the file containing your saves....internal storage/android/data/com.cryoxxx.oppaiodyssey (may be different on your device). Then literally copy the 'saves' folder to another custom folder, personally I copy them to a folder on my SD card.
Then, if ever you have to do a reinstall for example, just copy the save file from your SD card and replace the one in the games route directory.