Yu-Gi-Oh!

Season 1, Episode 20

Episode Title: It Came Out!! The Strongest and Final Trump Card

Air Date: 1998-08-15

Overview:

Kaiba's butler Daimon, an old man kept alive through machinery, duels Dark Yugi as the final Game Master. In the process, he reveals how Kaiba used to be, and implores Yugi to restore his kindness.