Aged counterparts are a group of monsters, which have been aged by "Time Wizard". Each aged counterpart has a card featuring their younger self. The method through which "Time Wizard" ages them varies.
"Dark Sage", which was released much later, was given a Summoning method closer to its anime self. It is a Main Deck card, Summoned by Tributing "Dark Magician" after applying the positive effect of "Time Wizard". Unlike its anime self, it is stronger than "Dark Magician" in terms of ATK and DEF. It has a weaker effect than its anime self.
If the player does not have the actual card for the aged counterpart, they can Summon the monster through Fusion Summon. If they have the actual card, they can Summon it normally, without performing a Fusion Summon.
Unlike other media, the younger counterpart, can be one of many cards.