Sugoroku Mutou is the grandfather of Yugi Mutou, who received the famous Millennium Puzzle as a gift from him. Sugoroku had retrieved this artifact from the tomb of Pharaoh Atem in his younger years. He runs the Kame Game shop, where Yugi and his friends often acquire various games they play. Sugoroku also taught Katsuya Jonouchi how to play Duel Monsters. His love for games is reflected in his name, "Sugoroku," which refers to a Japanese game similar to Backgammon. In fact, Sugoroku is the reincarnation of Siamun Muran, an ancient Egyptian vizier and right-hand man to Pharaoh Atem.
In the original manga, Sugoroku owned a rare Blue Eyes White Dragon card, which attracted the attention of Seto Kaiba. Kaiba stole the card and used it to duel Yugi. After Yugi reclaimed the card, Kaiba sought revenge by defeating Sugoroku in a duel at KaibaLand, tearing up his precious Blue Eyes White Dragon card. In the manga, Kaiba's revenge extended further, subjecting Sugoroku to virtual reality torture to force Yugi into participating in "Death-T," a series of lethal games and rides. Ultimately, Yugi defeated Kaiba, saving Sugoroku. The Duel Monsters anime combined these events, with Kaiba kidnapping Sugoroku and defeating him without further torture.
Things worsened for Sugoroku when Maximillion Pegasus removed his soul to compel Yugi into competing in his tournament. In the manga, Pegasus trapped Sugoroku’s soul in a video camera, while in the Duel Monsters anime, he imprisoned it within a Duel Monsters card. Sugoroku was freed once Yugi defeated Pegasus at the end of the tournament, continuing to offer support and advice to Yugi in future duels.
The Duel Monsters anime gave Solomon Muto another chance to participate in action during the KaibaCorp Grand Prix, where he competed under an alias. In the Japanese version, he used "Mask of Rock," while in the English dub, he adopted the alias "Apdnarg Otum," which is "Grandpa Muto" spelled backwards. He dueled Joey using an ancient-themed deck filled with rock monsters but was ultimately defeated by Joey.
Sugoroku reappears in episode 75 of Yu-Gi-Oh! GX, where he is kidnapped by Thunder (Ikazuchimaru) and Frost (Kourimaru).
