In the Yu-Gi-Oh! manga, Mai Kujaku is first introduced on the boat to Duelist Kingdom. Yugi, Jonouchi and Honda all find her extremely attractive, sparking jealousy and annoyance in Anzu. She challenges Dinosaur Ryuzaki (Rex Raptor in the dub) to a quick duel, and when she wins, she kicks him out of his own private room on the ship.
Once in Duelist Kingdom, she and Jonouchi duel. She pretends to be psychic, reading her cards face-down, throwing her opponents off their game. But Jonouchi discovers that she has merely sprayed her cards with different perfume. He exposes her "aroma tactics" and defeats her.
Later on in the manga, Mai has Ryuzaki duel Jonouchi for her, and if he wins, she will give him a rematch. Jonouchi defeats Ryuzaki (and wins his Red Eyes Black Dragon card), and Mai actually begins to soften and become friends with Yugi's group.
In her tent, while the boys are camping out on the ground, Mai tells Anzu that she used to be a dealer on a casino ship. Many men tried to win her affections with money, but Mai would outsmart them with her aroma tactics and win their money. She began to resent people, and quit, even though the job was quite lucrative. She then admits to Anzu that she wanted to spend time with Yugi and his friends because they remind her of herself at a younger, happier time. But before she can confess much else, she changes the subject to Anzu having feelings for Yugi, and after that she is abducted by Player Killer (Panik in the dub) and forced to duel him. Player Killer is an eliminator, and takes all of Mai's star chips, which are immediately won back by Yugi.
Later on in the story, after Yugi loses his duel and half his star chips to Kaiba, Mai steps in and repays him the star chips she owes him. The two of them end up facing each other in the finals, and Mai concedes the duel to Yugi, but not before admitting that she learned a lot from her defeat from Jonouchi. She admits she used her perfume trick because she was afraid to trust in herself.