Ayumu Aizawa has light green hair and green eyes. She serves as the computer expert and manager for the Circlet Bout club at Saint Union Academy, consistently wearing an oversized white coat inherited from her father—one of the developers behind the Mixed Reality System technology powering Circlet Bout.

Initially disinterested in the sport, Ayumu’s motivation changes after her father’s disappearance, driving her to analyze opponents and devise strategies to give her team tactical advantages. Her role focuses purely on analytical support during matches, avoiding direct combat.

When forced into competition, Ayumu wields a riot shield containing defensive arsenals. However, her lack of combat training and inability to dodge attacks render it ineffective, limiting her to defensive maneuvers.

A pivotal shift occurs when Ayumu requests a practice match against teammate Yuka Sasaki to uncover clues about her father’s vanishing. Here, she actively participates, departing from her typical support role.

Later, Ayumu investigates the unresponsive AI bracelet Siegfried—revealed as her father, Makoto Aizawa—after Yuka defeats it. Discovering its weapon data was deleted, she discloses Makoto’s identity to the team, linking him to the MR technology’s creation and its connection to top player Chikage Fujimura. Ayumu’s actions directly enable the team to secure a new weapon for Yuka post-Siegfried’s deactivation.

Her technical expertise and deepening personal investment in Circlet Bout remain central throughout, particularly in resolving mysteries tied to her family and the sport’s foundational technology.