Aki Izayoi (十六夜 アキ)

Aki is a Psycho Duelist who has extraordinary powers, which she blames the 'wretched mark', her Signer birthmark, for. She has the ability of making the effects of cards very real and her opponents take real physical damage. However, she does not want her identity known when she unleashes these powers, so she hides behind another identity of hers called the Black Rose Witch, since her ace monster is the Black Rose Dragon. The only person that seems to understand her best was Divine, who assisted her when she joined the Arcadia Movement, an organization of Psychic Duelists. However, after meeting Yusei in the Fortune Cup, her outlook on life changes bit by bit.
In Season 2 [Season 1 Arc 2], Aki's personality changes drastically. During her duel with Misty, the Earthbound Gods [Immortals] had penetrated so much damage to the Arcadia building, that Divine fell through the ceiling as a result of his duel with Carly. Aki sees Divine fall and she is distressed as she screams out his name. She is then seen falling herself and is caught by Jack. She is then taken to the hospital, where her parents, Hideo and Setsuko Izayoi, visit her. Seeing her parents, Aki becomes indignant and she unleashes her powers during her second duel with Yusei. Yusei, defeating her, helps her realize that she is able to control her own powers and is able to forgive her parents for their wrongdoings to her. Aki then agrees to fight alongside the other three Signers, Yusei, Jack, and Ruka in the Dark Signer vs Signer War.

Aki battles Misty once again during the war. However, Divine appears to her during the duel, reawakening the Black Rose Witch spirit inside of her. Aki relentless battles Misty before Misty discovers the truth about her brother Tobi's death from Divine via Duel Disk Communicator that Yusei had planted in. Misty becomes enraged and allows her Earthbound God [Immortal] to swallow up Divine whole, surprising everyone, Aki especially, very much. Aki then returns to normal and is able to defeat Misty. Misty is able to forgive Aki before she finally turns to dust. Aki is last seen in that episode holding a photo of Misty and her brother, Tobi, after her personality permanently changes.

During Yusei, Jack, and Crow's battle against Godwin, she is seen helping them by destroying Mekai No Oh's minions that were trying to harm Yusei, Jack, and Crow by using Black Rose Dragon.

Towards the end of 64, she is seen holding up a photograph of Misty's photoshoot, implying that the two had developed a friendship.