Mana

It is revealed in the final season of Yu-Gi-Oh! that Mana is the past reincarnation of the Dark Magician Girl.

History
Mana is a young magician in training at the Dawn of the Duel arc's beginning who serves the priest Mahado. Later when Yugi discover her Yugi explains about the card game back home commenting on her reference to Dark Magician Girl. Mana later helps them to defeat Zorc. It isn't explained in either anime but after the gang leaves the Memory World it is believed that she vowed to protect the modern-day pharaoh Yugi.