Aiho Yomikawa teaches physical education at an Academy City high school while also serving as a lieutenant in Anti-Skill Branch 73, the city's law enforcement. She possesses a tall, slim frame with notable proportions, dark blue hair often in a waist-length ponytail, and teal eyes. Her attire alternates between a tight green jersey for teaching and standard Anti-Skill tactical gear—including combat armor and an SG-550 assault rifle—for operations. Her personality merges kindness with stern professionalism. Deeply committed to child welfare, she refuses to use weapons against minors regardless of their actions due to an undisclosed traumatic past event, extending this protective stance to all Academy City esper students. Despite this gentleness, she employs rigorous training methods with students and harshly disciplines her junior officer, Tessou Tsuzuri, for patrol lapses. Off-duty, she displays a carefree, cheerful demeanor, frequently socializing with colleagues like Tsukuyomi Komoe and Kikyou Yoshikawa over public baths, beer, and meals, often becoming publicly intoxicated. She enjoys teasing Komoe about her childlike stature and exhibits a relaxed attitude towards nudity around teenagers. Stress triggers intense cleaning sprees that sometimes lead to recklessness. In combat, Yomikawa uniquely wields protective equipment like riot shields or helmets as blunt weapons against adversaries, rationalizing their safety design makes this ethically permissible. This tactic earned her the moniker "the woman who uses comedy-like methods to solve problems that could end as a tragedy." She possesses formal military training in firearms, hand-to-hand combat, and powered suit piloting. Background details are limited but note a longstanding friendship with Kikyou Yoshikawa, who entrusts her with child care during emergencies. She once attempted the Anti-Skill entrance exam with the Tokiwadai Dorm Supervisor; both failed after assaulting instructors, though she later apologized and secured membership. Prior to the series, her Anti-Skill unit dismantled the Special Ability Institute where Accelerator resided until age nine. She lives in Family Side, teaching elite classes adjacent to Komoe's. Her chronological involvement includes: first appearing during the Kazakiri Hyouka Arc, coordinating Anti-Skill against Sherry Cromwell's golem and aiding Kamijou Touma despite severe injuries. In the Tree Diagram Remnant Arc, she guards Accelerator and Last Order during their bath and assaults the external Science Association group targeting the remnants. During the Daihasei Festival, she performs peacekeeping duties and socializes with Komoe. Her most significant development occurs in the Academy City Invasion Arc, where Yoshikawa tasks her with sheltering Accelerator and Last Order. She provides them housing, helps Accelerator locate a missing Last Order using Anti-Skill resources, and challenges his self-perception as irredeemable. She later collapses during Vento of the Front's invasion due to Divine Punishment effects. Subsequently, she becomes the legal guardian for Accelerator, Last Order, and Misaka Worst.