Aiho Yomikawa is a Physical Education teacher at an Academy City high school and an Anti-Skill lieutenant serving in Branch 73. She possesses a tall, athletic build (175 cm), typically wears a green tracksuit, and ties her dark blue hair in a ponytail. Her law enforcement approach is defined by an unwavering personal principle: she refuses to aim weapons at children, regardless of their abilities or threat level. This principle stems from a past traumatic incident during Anti-Skill duties where she drew a weapon on a child, resulting in the child's death; the resulting guilt solidified her resolve never to repeat such an action. Instead of conventional weapons, she employs protective gear like helmets or riot shields to subdue delinquents or rogue espers. This method earned her the informal titles "the woman who uses comedy-like methods to solve problems that could end in tragedy" or "the woman who makes the serious comical," allowing her to resolve violent situations without violating her moral code. Her significant combat proficiency enables her to restrain powerful espers like Accelerator or Kakine Teitoku through presence and dialogue alone, and she has demonstrated physical strength capable of cracking concrete walls. Beyond her duties, she maintains a cheerful, carefree demeanor. She enjoys social activities such as public baths, eating out, and drinking beer with friends, particularly colleagues Komoe Tsukuyomi and Yoshikawa Kikyou, though she is prone to drinking to excess. She often teases Komoe about her childlike appearance. Her coping mechanism for stress involves intense cleaning sprees, sometimes leading to recklessness like misplacing keys. She exhibits no embarrassment about nudity around teenagers like Accelerator, whom she views as children, as demonstrated when he accidentally encountered her, Last Order, and Yoshikawa showering. Personally, she acts as a legal guardian, providing shelter for Accelerator, Last Order, Misaka Worst, and occasionally Yoshikawa Kikyou. She resides in a four-bedroom faculty condominium, creating a crowded but functional living space informally dubbed "Yomikawa’s House" in fan depictions, reflecting its role as a refuge. She is an efficient home manager, known for preparing diverse meals—including hamburg steak—using a single rice cooker, prioritizing practicality over specialized tools. Her background includes dismantling the Special Ability Institute where Accelerator was confined until age nine. She failed her initial Anti-Skill qualification test alongside the Tokiwadai Dorm Supervisor after both assaulted the instructors, though she later passed after apologizing. Her longstanding friendship with Yoshikawa Kikyou enables Yoshikawa to entrust her with caring for children like Accelerator and Last Order during crises. Key chronological developments include: * During the Kazakiri Hyouka Arc, she led Anti-Skill operations against Sherry Cromwell's golem in an underground mall, sustaining injuries while protecting civilians and collaborating with Kamijou Touma to ensure Hyouka's safety. * In the Academy City Invasion Arc, she became Accelerator and Last Order's primary caretaker after Yoshikawa sought refuge at her apartment. A bath scene underscored her view of Accelerator as a child. She later aided Accelerator in locating Last Order using Anti-Skill technology and challenged his fear of reciprocating goodwill, prompting him to reconsider his self-perception. She collapsed due to Vento of the Front's Divine Punishment spell. * In the Necromancer Arc (A Certain Scientific Accelerator), she refused orders to fire on student assailants armed with an experimental water cutter, prioritizing her vow over protocol, reinforcing her commitment to protecting children amidst direct threats. Her role consistently bridges law enforcement, education, and surrogate motherhood, emphasizing protection and rehabilitation over force.