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.
Season 2 [Season 1 Arc 2] 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.Season 3 [Season 2]
In Season 3 [Season 2], Aki is seen as a very amiable character who gets along well with Yusei and the gang, especially the twins with Rua even calling her "Big Sister Aki" at times. In this season, after Aki had experienced a riding duel between Yusei and Sherry after Yusei had been kidnapped and rescued by her, she becomes inspired to become a D-Wheeler and applies for a license. Her first few practice runs fail however, so Yusei assists in helping her accelerate her D-Wheel in the form of ice-skating. Aki, after this event, improves on her D-Wheel riding immediately. After defeating Ushio in the Riding Duel exam, she gains her license as a D-Wheeler. However, as inexperienced as she was, she was the first one to step forward to take Crow's place in the WRGP tournament after Crow had hurt his shoulder bone in a highway accident during a practice run. At first, Crow is upset that Aki 'knew' what he was going through, but he is later seen helping Aki with her D-Wheel Riding. In the actual tournament, she battles against Andore of Team Unicorn after Jack had taken a serious fall from the damage inflicted in his battle against Andore. Aki manages to bring down Andore's life points by a measurable amount before she summons Stardust Dragon, which was given to her by Yusei, who told her to use it. She increases her life points to 4000 LP before she passes the baton to Yusei. She later feels distressed because she felt she didn't contribute much as a D-Wheeler to the team, but Crow, handing her a cup of coffee, helps her to think otherwise, telling her that as much as he, Jack, and Yusei have participated in Riding Duels, they were all inexperienced D-Wheelers in a way, giving Aki some inspiration. However, as Aki was trying to improve her D-Wheel riding skills on the highway, Team Catastrophe uses Dark Knight Hook's effect to crash her. Although Aki summoned Rose Tentacles, her powers does not activate and she crashes, leaving her unconscious. As of yet, she has still not regained consciousness.Her first name in Japanese-Aki means Autumn