Kyouka Izumi, a teenage girl with indigo-black hair styled in low twin-tails accented by floral pins, possesses pale skin and piercing blue eyes that shift from a muted hue to vivid clarity after her integration into the Armed Detective Agency. Her signature attire features a crimson kimono embroidered with sprout motifs, fastened by a golden datejime belt, paired with white socks, sandals, and wrist guards. She often carries a rabbit plush and a cellphone pendant, though her wardrobe adapts to missions—donning disguises, military police uniforms, or ceremonial garb as needed. Orphaned young, Kyouka inherited her mother’s ability, Demon Snow, during a fatal ambush by assassins who manipulated her parents’ blood. The incomplete transfer bound the ability to her phone, requiring external commands. Recruited by the Port Mafia, she trained under Kōyō Ozaki, earning infamy as the "Thirty-Five Count Murderess" for executing 35 targets in six months with emotionless precision. Her trajectory shifted during a train-bombing mission with Motojirō Kajii, where Atsushi Nakajima thwarted her self-sacrificial detonation attempt. His intervention spurred her defection to the Armed Detective Agency. Under Yukichi Fukuzawa’s guidance, she stabilized her link to Demon Snow, pursuing redemption through non-lethal tactics while retaining tactical ruthlessness to protect allies. Kyouka navigates reconciling her violent history with her resolve to safeguard others, forging uneasy alliances with former foes and risking her life to neutralize threats like the Guild’s airship. Despite her lethal prowess, she displays childlike quirks—savoring tofu, crêpes, and leisurely outings—marking her transition from detached weapon to multifaceted individual. Skilled in acrobatics, swordsmanship, infiltration, and anatomical precision, she wields Demon Snow—a spectral swordsman initially phone-dependent but later mastered through will. The ability’s origins, tied to her mother’s sacrificial death, resurface during conflicts with the Decay of the Angel and Hunting Dogs. Haunted by unresolved trauma, Kyouka once believed herself culpable for her parents’ murders until flashbacks and Kōyō’s testimony revealed their assassination via manipulated adversaries. Her growth is punctuated by clashes with Ryūnosuke Akutagawa, asserting her evolution beyond a tool of destruction. Bonds with Atsushi and the Agency anchor her sense of belonging, though she grapples with self-worth, mirroring his journey yet diverging in her acceptance of past actions. In subsequent missions, she confronts crises like the Agency’s framing as terrorists, collaborates with the Port Mafia, and battles global threats such as the vampire plague. Each trial reinforces her commitment to Yokohama, culminating in daring sacrifices that cement her role as a steadfast Agency protector.