Kujaku Mai, hay Mai Valentine trong phiên bản lồng tiếng Anh, là nhân vật phụ trợ thường trực trong manga và series anime thứ 2 của Yu-Gi-Oh!.
Mai's character design was overseen by Kazuki Takahashi. In the anime, in Duelist Kingdom, Mai wore a short-sleeved purple coat over her white tube top, which shows her belly button, along with recurring purple high-heeled boots. From Battle City on, she changed to a sleeveless light purple vest and a white tank top and wore long white fingerless gloves. She wears a dark purple mini-skirt and a deck holder strapped to her thigh in the Duelist Kingdom and Battle City arcs, but in Waking the Dragons, she wears dark purple shorts and now wears purple gloves. In the Yu-Gi-Oh! The Movie: Pyramid of Light, she is seen in an outfit similar to the one in one she wore in Waking the Dragons. However her top is white/grey instead of purple.
In the manga, in Duelist Kingdom, she largely wore the same outfit as the anime, but her top was open, revealing the middle of her chest and held together using strings, like a corset. In Battle City, she changed to wearing a black leather vest and mini-skirt, and wore a similar tube top as her Duelist Kingdom self, but with the front closed.
In the English anime, her cleavage and lines of cleavage are digitally reduced or erased and her skirt is lengthened.
At the beginning of the series, Mai is a self-absorbed woman who is only set out for prize money, personal satisfaction and power. She was also very arrogant and prideful of her dueling skills and looks.
At first, Mai often used her beauty to seduce men into giving her what she wants and making them her tools. She used her beauty to easily steal Rex Raptor's luxury room on the cruise to Duelist Kingdom by offering him a kiss if he could beat her in a duel, and later manipulated him into dueling Joey for her as revenge on Joey for defeating her in an earlier duel.
Mai is extremely lonely and at first, is convinced that she doesn't need friends. At one point, she believed her "Harpie Lady" cards were the closest she would ever have to friends.
Mai's selfish attitude and outlook on life continues until she meets and finds meaning with Yugi Muto and his three best friends. After she meets them and Yugi fought Panik for her to regain her Star Chips, Mai begins seeing Yugi, Joey Wheeler, Tristan Taylor, and Téa as her friends. She even offered Yugi her extra Star Chips so he could enter the Duelist Kingdom's Finals and rescue his grandfather after Yugi lost to Kaiba, and gave Joey her entry fee card for the finals when his was stolen by Bandit Keith. From there, she continued meeting up with the four on occassions and helping them out from time to time on their adventures.
Mai's feelings of loneliness and emptiness return when she is forced to face Marik Ishtar in the Battle City finals. Marik enters her into a Shadow Game, where with each of her monsters destroyed she begins losing the memory of a former friend. In the end, Marik defeats her and leaves her mind trapped in the Shadow Realm for a long time while she continues feeling more and more alone, miserable, and isolated every minute, until Yugi finally defeats Marik in the final round and releases her.
After being freed from the Shadow Realm and gone separate ways from her friends for a while, Mai's wins become empty to her and her feelings of loneliness return even more. Eventually, she is unable to cope with the mental trauma and turns against her friends, joining the evil Dartz to assist him in his quest for power. However, Joey seems to eventually return her to her old self and she recovers her self-esteem and pride as a true Duelist, but was unable to face her former friends again after what she had done to them.
In the Japanese version; Mai typically uses a quite informal manner of speech. She commonly omits honorifics when speaking with others, but addresses Anzu and Shizuka as "-chan." She uses the informal and potentially condescending "anta", a contraction of the more formal "anata" (similar to the English "honey"). She uses the personal pronoun "atakushi", which tends to be a more elegant, if not older, form of self-reference.
"Kujaku Mai" means "peacock dance" in Japanese. Her name in the English anime is a pun of "My Valentine".