Yami Yugi is the spirit of the ancient Pharaoh residing in the Milennium Puzzle. His past is shrouded in mystery.

3,000 (5,000 in the dub) years later, Yugi Mutou, after trying to solve the puzzle for eight years, awakens the Pharaoh from his slumber, although Yugi does not realize this until much later in the story.

At the end of Duelist Kingdom, the Pharoah asks Yugi to help him recover his memories and Yugi agrees to help him.