Yu-Gi-Oh Super Book: The Story, Anime, Characters and Games.

Yu-Gi-Oh! tells the tale of Yugi Mutou, a timid young boy who loves all sorts of games, but is often bullied around. One day, he solves an ancient artifact known as the Millenium Puzzle, causing his body to play host to a mysterious spirit. From that moment onwards, whenever Yugi or one of his friends is threatened by those with darkness in their hearts, this 'Dark Yugi' shows himself and challenges them to dangerous 'Shadow Games' which reveal the true nature of someone's heart.