True to her appearance, Maico acts like a kindly grandmother when encountered by Yugi. She speaks about her grandchildren a lot, even saying that when she beats Yugi, she'll be sure to buy them lots of toys. Like the other Card Professors, she's fairly confident with her own abilities as a Duelist. Still, she's shown to be very respectful to Yugi, in the end saying she enjoyed their Duel.
Her grandchildren are huge fans of Duel Monsters, and taught her to play at some point in the past.
At another unknown point, she joined the Card Professor mercenary group, and like the others, is hired by Tenma to stop Yugi's ascent of the KaibaCorp main building.
She first appears sipping tea, anticipating Yugi's arrival. He then comes across her after being unable to unlock the next door, and mistakes her for a kindly old woman. Yugi is quick asks her if she's seen a man with a Duel Disk on anywhere nearby, but she says she hasn't, and asks Yugi if he's looking for someone to Duel. She quickly reveals that she's a card professor, and says that the only way that Yugi can go on is to Duel her. She reveals her special Duel Disk, one that's implemented into her wheelchair and then Duels, and loses, to Yugi. After the Duel, she watches silently as Yugi runs off to Duel a possessed Gekko Tenma.
Maico's Duel Disk is similar in appearance to the one used by Jack Atlas.