Apocalyptic Wasteland Simulator

In the year 1257 of the Federation Calendar, Chen Pingchuan, who has crossed into a different world for three years, gets the Apocalyptic Wasteland Simulator. Through information obtained from the simulator, a sudden disaster will strike Spring City in a year. Accompanied by highly radioactive red rain, a type of mutated creature called Black Demon will be born. With the simulator, Chen is in a better position to survive, but he also wants to find out the secrets of the girl he meets in simulations. Simulator: [She left you a small bottle of liquid with an unknown effect and a note with just two short lines written on it.] [Avoid the red rain!] [Forget me!]