Yoriko Yagami is Kirika Kusanagi and Akane Asamiya's best friend and classmate attending Kyoto High School in Japan. Yoriko like the other girls, were involved in an incident during a field trip at a local genetics lab, where they witness a fight between a British MI6 operative and a saboteur; resulting in nearby spilled chemical fumes affecting the girls, causing their brains to slightly mutate giving them a mental "alert radar" sense with telepathically warns them of danger. Yoriko and the girls would later join MI6 as their undercover task force against the criminal organization SABRE. Yoriko, the resident tomboy of the trio, takes on the "dirty portion" of the girls' various missions across the globe as the team's "muscle". When not at school or engaging in espionage assignments, she lives and works at her Shinto Priest father's temple as a miko (shrine maiden) who conducts and performs various exorcism stints to local clients, despite having a frustrating time at the job and considers it a major annoyance.

        Yoriko considers herself as the "tough gal" and the hot-headed of the trio. She always going head first into dangerous situations without thinking and has a knack for mayhem and blowing stuff up on missions with her hi-tech weapons she "borrowed" from Professor Harold Higgins' R&D department. She also is prone to starting fights as school, especially putting up her fists as local bullies picking on nerds. She also hates perverts, especially when she punches an unfortunate hapless leech with lethal (comical) force anytime that person attempted to look under her skirt. Despite her many flaws, she is still loyal to her friends and soon trust Kirika's rational thoughts and a secondary opinion. Her favorite hobbies include dirt biking and rollerblading. Her favorite foods are spicy Mongolian pork and sweet and sour chicken.

        Like her friends Kirika and Yoriko, Akane possesses, as the result of the fateful lab accident, a sixth-sense "danger" radar, a psychic radar that warns hear of nearby danger or immanent physical harm. She also develop superhuman agility and reflexes from the accident. She is a seasoned and trained athlete, biker and swimmer. As a top agent in the MI6, she gains access to agency's prototype gadgets, weapons, vehicles and aircraft. Like her friends, Akane carries a secretly concealed utility belt containing such items such as smoke bombs, non-lethal shurikens, a microfilm camera, a miniature MP3 recorder, and an optional sleep dart wrist gun. She is a gifted expert in experiment hi-tech weapons and explosives, including her preferred weapons of plasma rifles and plasma grenades, all which she "borrowed" from MI6's R&D department without the knowledge and/or permission of Professor Higgins, though she have not brought back the equipment back in one piece. She is a trained expert in Greco-Roman wrestling, boxing, karate, tae kwan do, and Thai kickboxing. Since she is trained as a Shinto priestess, she has various training in exorcism and anti-demon magic and spells.