In this game, you follow a young soulless shell for you to self-insert into man who is... reverse isekai'd if you will. A world of magic and fantasy builds itself around him. The setting allows the story to be relatively grounded as the world is the one you know and love, yet magical elements have seeped their way inside.
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