Each duel is performed in various themes inside Kaiba Land such as Roller Coaster theme, Amezon theme, Horror House etc. Then a strong duelist named Sieg Llyod appears. He shows his great performance by beating Haga and Ryusaki in merely a turn. On the other side, there is a hacker who tries to send virus into and mulfunctions KC's main computer system. Kaiba tries his hard to figure out who the hacker is and what his purpose is. Finally, Kaiba realizes that Sieg Llyod is, in fact, the hacker and is a member of Schraider family that is a rival company against Kaiba Corporation. Although Sieg is disqualified from the game, his brother, Leon, can reach the final battle against the defending champ, Yugi. Sieg forces Leon to beat Yugi for Schraider family, giving him an invicible card. When Leon plays that card, virus is sent into KC's main computer. This is the purpose of Sieg who joins KC Grand Prix to destroy Kaiba Corporation. However, Yugi can win the game and keep his title of duel king.