Kemo worked for Maximillion Pegasus during the Duelist Kingdom tournament. He apprehended Mokuba Kaiba after Mokuba's Duel with Yami Yugi. Yami then challenged him to a Duel for Mokuba's freedom. Since Kemo did not play, he arranged for Ghost Kaiba to Duel Yami. Although Yami won, Kemo still took Mokuba back to Pegasus.
Kemo was confronted by Seto Kaiba after Kaiba entered the island. Kemo held a gun to his head but Kaiba disarmed him using the card "Gyakutenno Megami" to jam his gun (this was cut from the dub). Kaiba then forced Kemo to take him to Mokuba's cell.
Kemo later acted as the guard at the entrance to Pegasus' castle and attempts to stop Téa Gardner, Tristan Taylor and Bakura Ryou from entering as they were not Duelists. Mai Valentine then flirted with him, distracting him long enough for the others to dash in, closing the door behind them.
During Yugi Muto and Joey Wheeler's first stay in the Virtual World, Kemo attempted to break into the room where their bodies were. Téa Gardner and Tristan Taylor put up a desperate defense to stop them, using furniture to block the door. When everyone awoke after the Big Five had been defeated, Kemo fled in order to warn the Big Five members.
In the original Yu-Gi-Oh manga, Kemo was originally introduced as one of Kaiba's bodyguards. Later, in duelist Kingdom, it is revealed that Kemo was working for Pegasus the entire time. Although this is never mentioned in the anime, he can still be seen working for Gozaburo Kaiba in flashbacks.