Feng Liu

A young man named Liu Feng gains the ability to travel between our world and another world once a day. Using this ability he is able to make a good living selling items from our world to this one. Discovering that he needs a living area to continue his business, he decides to buy a small bar that is out of the way. By pure chance, a Baron spending time in said bar overhears him and gives him an offer he can't (and won't let him) refuse, buying his city of Xi Yang as well as grant him a noble title of Baron.

After this city, which is quite run down, is sold to him. Liu Feng goes about using his knowledge and access to tech from our world to greatly improve the city and its citizens, while dealing with the jealously of other nobles.