There was once an ordinary and remote village to which a man, who had no relatives, appeared. Since then, everything has changed. Labor became pleasant, people stopped starving and became healthier, resulting in population increase. On top of that, the village started to flourish in trade. A time of huge change and considerable turmoil was about to begin, a revolution that no man could turn a blind eye to. In the ancient bronze era, even distant than medieval times, a certain blacksmith was yet to make his great effort.

One day, Wataru stumbles upon a gate that allows travel back and forth between Japan and another world. Beyond the gate is a fantasy-like world. Seeing a town whose civilization was undeveloped in many respects, he realizes the potential for great profit. In other words, bringing sugar, spices, coffee, hygiene products, and the like to the other world and making a fortune. Striking it rich in the other world, Wataru suddenly realizes something when he sees a potion for sale: "Maybe this would be better in the other world?" Wataru makes a killing bringing potions that instantly heal the user's wounds to earth. He also buys beautiful slaves, and before long, he is doing great on earth too.