I Was the Only Underground Emperor

Jack was a gangster from the lower class of Chicago. He lived in a poor neighborhood and might die in a gang fight or gunfight at any time.
Because of some accidents, he had mastered a super ability that could travel back and forth between the real world and the different world of Niles kingdom.
In the real world, everything that was common became treasures when they were taken to Niles kingdom, which caused a sensation.
Jack changed the coke to a divine weapon from a stranger old man so that he could learn magic more easily; He traveled to the desert of a different world and saved the caravan or wizard, getting gems, magic, and so on. There was a pest infestation in the different world. However, the real world's insecticide had a miraculous effect on these pests, making Jack a hero in an instant.
Jack traveled between two worlds and got the things in the real world to the different world, in exchange for treasures, magic, and other things. Then he took the treasures back to the real world and turned them into money, which caused a lot of trouble. But because he had magic, he dealt with and pretended to be powerful. From then on, he became the hero of a different world. There were many beauties for the underground emperor in the real world.