Ayako Mochizuki is a central character and one of the primary retainers serving Tokiyuki Hojo, the protagonist of the story. She is a young girl, around the same age as her master, but her physical presence is remarkable; she possesses an unusually tall and robust stature that often leads others to mistake her for being much older. Her appearance is typically marked by long black hair, often tied back with a ribbon for battle, and she wears a traditional white kimono top paired with a red hakama skirt.

Ayako is introduced as the illegitimate daughter of Shigenobu Mochizuki, a prominent general serving the Suwa faction. Despite her status, she shares a warm and affectionate relationship with her father, who is immensely proud of her strength. Her family background is one that values raw power, reflected in the saying within the Mochizuki clan about breaking ribs to become stronger. She was personally selected by the clairvoyant Yorishige Suwa to become one of Tokiyuki's closest companions and a member of the group known as the Elusive Warriors.

In terms of personality, Ayako is defined by her cheerful, energetic, and remarkably straightforward nature. She is fiercely loyal to her friends, especially to Tokiyuki, whom she is determined to protect at all costs. Her honesty is so direct that she openly declares her admiration for her lord, often stating her aspiration to bear his children one day. She draws inspiration from the legendary female warrior Tomoe Gozen, whom she idolizes and wishes to emulate. This bright and unshakable spirit makes her a source of morale for the group, as her enthusiasm and artistic talents help keep the warriors' spirits high during difficult times.

Ayako's role within the narrative is that of a front-line combatant and a steadfast guardian. While she is not depicted as a refined or technical swordmaster like some of her peers, her primary asset is her immense, almost superhuman physical strength. She fights with a brutal and effective style, relying on overwhelming power rather than finesse. She is proficient with various weapons, including the sword and the naginata, and eventually receives a custom-made, massive square iron pillar fitted with a blade named the "Yomonokedamono" or "Beast of the Four Directions," which becomes her signature weapon.

Beyond her combat abilities, Ayako possesses a unique and highly valued talent in the arts. She is a master of dengaku, a traditional form of music and dance. Her physical strength allows her to perform incredible feats, such as playing five different musical instruments simultaneously while dancing. This artistic skill serves both as entertainment and as a way to captivate and inspire allies, demonstrating that her value to the group extends far beyond her prowess on the battlefield.

Throughout the story, Ayako develops from a capable retainer into a recognized leader. Her loyalty and contributions are formally acknowledged when she is accepted as the heir to the Mochizuki clan and bestowed with the title of Hime-Yasha, or Demon Princess, making her the only one among Tokiyuki's companions to govern her own domain. Her relationship with Tokiyuki evolves as she remains his devoted protector, and her dream of uniting with him is ultimately realized, solidifying her role not just as a warrior, but as a key figure in the restoration of the Hojo clan's legacy.