Like other Knights of Hanoi, Kyoko is fiercely loyal to Varis and will carry out the ambitions of Dr. Kogami to the very end. Like Aso, Kyoko shows a degree of sympathy and mercy as seen when she felt remorse watching the six victims suffer during the Hanoi Project and when she had a change of heart and released the Another virus victims after her defeat by Blue Angel.
10 years before the present, Kyoko was one of Dr. Kogami's assistants who helped him plan and execute the Hanoi Project. Together with Kogami, Aso, and Dr. Genome, she 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, she helped recreate his consciousness inside the network, faithfully serving as a Knight of Hanoi ever since.
After losing to Blue Angel, Kyoko activated the removal program in a change of heart, curing all the Another Victims. Consequently, the Knights of Hanoi 'purged' her shortly after for releasing the removal program.
Following the collapse of the Tower of Hanoi, Kyoko was sentenced to a maximum security prison and was placed under strict security, but later escaped and returned to the Knights of Hanoi thanks to help from Varis, Spectre, Aso and Dr. Genome.