Like many other Knights of Hanoi, Aso is a ruthless individual who seeks to acquire and destroy the Ignis, even willing to hold hostages or infect duelists with the Deleted virus to do so. He is fiercely loyal to Varis and will carry out Dr. Kogami's ambitions to the very end. Despite holding hostages, Aso shows a degree of sympathy and mercy as seen when he and Clarissa expressed remorse watching the victims suffer during the Hanoi Project and when he released Naoki Shima after he lost. He is also a very methodical and diligent person evidenced by the way he duels and during his discussion with the other Knights following the Tower of Hanoi.
10 years before the present, Aso was one of Dr. Kogami's assistants who helped him plan and execute the Hanoi Project. Together with Kogami, Clarissa Turner, and Dr. Genome, he helped create the Ignis: six AI with free will based on the Lost Incident victims and the Duel Monsters attributes. When SOL Technologies infected Dr. Kogami with a computer virus to cover up the Hanoi Project, he helped recreate his consciousness inside the network, faithfully serving as a Knight of Hanoi ever since.
Aso, Dr. Genome, and Clarissa Turner planned and executed the Deleted Incident, infecting duelists of LINK VRAINS with a computer virus to lure out Playmaker and acquire his Ignis. After Clarissa Turner and Dr. Genome were defeated, Aso decided to face Playmaker himself, holding Naoki Shima hostage to draw him out. Upon losing, Aso tries to warn Playmaker of the dangers regarding the Ignis before vanishing. After the duel, he goes into a coma alongside his comrades and Varis prepares to face Playmaker. After the Tower of Hanoi is stopped, he and his comrades are restored to normal.
After the events of the Tower of Hanoi and rebuilding of LINK VRAINS, Aso met up with Varis in real life to devise a plan to save Kyoko, along with Dr. Genome and Specter. They successfully infiltrated the prison facility Kyoko is held and rescued her, logging into LINK VRAINS as they blew up the facility. He later appeared with Varis in Lightning's world and started dueling Windy's army of Echos, defeating one of them with Motor Worm Spreader Queen. He eventually beat them all with Kyoko and Dr. Genome and went to Varis in the middle of Varis and Windy's duel, expressing confidence in his leader's ability to win. After Varis finished Windy with Borreload Savage Dragon, he worked with Kyoko and Dr. Genome to infect Windy with a virus that attempts to erase him. After Lightning flees to heal Windy, Aso then left with Varis to leave Playmaker and SOL Technologies to deal with the pursuit of Lightning.
Aso plays a "Motor Worm" Deck. His strategy focuses on distrupting the opponent's strategies by changing their monsters to Insect-Types. While his opponent's monsters are Insects, he can utilise his Continuous Spells to minimise his opponent's ability to utilise their monsters, while providing himself benefits.