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.