One faction of the Tomb Keepers watched over the Necklace and the Rod. After their father was murdered, Ishizu owned the Necklace.
When first introducing herself to Kaiba and showing him the stone tablet brought from Egypt, Ishizu uses the Millennium Necklace to let Kaiba see a glimpse into the past, particularly over the battle between the pharaoh and a sorcerer that was once the pharaoh's friend.
Using it to foresee her victory against Seto Kaiba in the Battle City tournament, Ishizu eventually handed the necklace over to Yugi when her vision failed to come true (which was partly due to the Millennium Rod giving Kaiba a vision that convinced him to change his strategy), knowing that the necklace would be needed for Yugi to defeat and release her brother from the growing evil inside him. After Joey became critically injured after his Duel with Yami Marik, the necklace showed Yugi a vision of him and Joey Dueling, giving him the courage to fight on.
After the Ceremonial Battle, the Necklace, along with the rest of the Items, were buried underground.
The necklace allows its wearer to see through time, offering vivid glimpses of the ancient past and near future - futures whose outcomes can only be altered through the inadvertent interference of other Millennium Items.
It can also protect its wearer from the shadow magic of other Millennium Items.
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