Welcome to the world of Yu-Gi-Oh! Growing up in a world of toys with which Yugi Muto's grandfather does his business, one day his grandfather offered him a puzzle, called the millennium puzzle, which supposedly has never been finished and contains something terrible. Yugi, who is very special, manages to complete this pyramid-shaped puzzle. While Yugi is rather naive and nice, maybe even a little too much, he suddenly becomes darker, and in strange games, he becomes the master and begins to humiliate his opponents by crushing them and leaving them no chance.