Ayanosuke, born Ayame, is the lone survivor of Kasumi village's destruction, annihilated by a three-headed demon monster on Nobunaga Oda's command. Her brother Shinnosuke sacrificed himself to secure her escape, entrusting her with their clan's enchanted kodachi, one of three mystical weapons prophesied to defeat Nobunaga. After losing her home and family, she forged the gender-neutral identity "Ayanosuke" to conceal herself while pursuing vengeance.

Her quest drives her to find the remaining enchanted weapons and their wielders: Sakon Hayate of the Hyuga clan and Ryoma Kogure of the Hagakure clan. Initially fueled by rage and grief over her brother and her people, her purpose broadens into ending Nobunaga's demonic tyranny across Japan. She forms a deep bond with Sakon, building mutual trust and unspoken romantic feelings, though their connection remains unresolved due to his sacrificial death.

She endures repeated personal losses, witnessing Ryoma's sister Kikyo die in her arms after shielding her from the Oboro ninja Jinnai. These traumas compound her pain but fortify her determination. Struggling with emotional vulnerability amidst sorrow and anger, she displays resilience in combat, relying on agility, tactical skill, and her kodachi. Her fighting style proves effective yet demanding, requiring significant effort against foes like the Oboro warriors.

In the final confrontation, she unites the three enchanted weapons with Sakon and Ryoma to defeat Ranmaru, the demon manipulating Nobunaga. Both Sakon and Ryoma perish; Sakon intercepts a fatal blow meant for her. Standing alone once more, she succeeds in eradicating the demonic threat. Her arc concludes as the prophecy's sole fulfiller, having avenged her clan while bearing the weight of solitude and sacrifice.