This game is a 2D first person hentai game where players play as the busty pig tailed Maiko Umiya. During the game, while living her normal life, Maiko unknowingly trains herself to survive a fight that previously killed her in the future according to some mysterious time travelers. This game is not meant to be super serious or realistic. A lot of things in the game are intentionally comical or exaggerated.
In order for you to be able to install this game, you need to enable (allow) installation of applications from unknown sources (Unknown sources) in the phone settings. Usually this item is in the Security section