itch.io

Uh not sure what you mean. You literally dont need to grind stats for scenes like I said. Interact with the girls and follow the main story. Each of the main girls have training events you can do. Their profiles will say if they are available or not 

It applyes to everything as long as you have access to save files. If you are using apk version of the game save files usualy can be found in "Andoid/data" directory, in game's folder. If your android is 11 or higher you will need file manager that can give you access to "android/data" directory (for that purpose I usualy use ZArchiever, as it is not only good archiever, but also great file manager). If you are using JoiPlay emulator things are much easyer - saves are in the folder with game.