Saiai Kinuhata is a Level 4 esper operating within Academy City's dark side as part of the organization Item under Mugino Shizuri. Approximately 12 years old, she sports short brown hair cut in a bob. Her attire varies, including a short white sweater dress designed to prevent exposure during movement, or alternatively, an orange hoodie with hot pants. Her origins lie in the Dark May Project, an experiment that forcibly implanted Accelerator's thought patterns into young espers to replicate his vector control. Originally an atmospheric control-type esper, this project altered her ability into Offense Armor (Nitrogen Armor). This power manipulates atmospheric nitrogen to form a dense, compressed barrier centimeters thick around her body. The barrier automatically deflects projectiles and physical assaults, offers limited sensory disruption via air currents, and grants enhanced strength – enabling feats like lifting cars or shattering walls with punches. Its effective range remains minimal. A key weakness stems from powerful impacts exploiting her small frame to knock her down, and environments depleted of nitrogen compromise her defense. She carries a liquid nitrogen canister to mitigate this vulnerability. Kinuhata is also proficient in marksmanship and combat tactics, wielding handheld anti-tank missile launchers effectively. Kinuhata blends combat professionalism with eccentricity. She exhibits ruthlessness on missions, willing to kill or torture without hesitation. Off-duty, her demeanor relaxes; she enjoys B-movies and C-movies, collects used tickets, and teases allies like Hamazura Shiage about his reactions to suggestive topics. Her speech is marked by frequent use of "super" (or "ultra"), a verbal tic replacing potential expletives due to the Dark May Project's alterations. She harbors a complex about her chest size relative to other Item members and reacts violently when angered or embarrassed, such as attacking Hamazura after accidental exposures. Despite an abrasive exterior, she demonstrates loyalty to Item, visiting Takitsubo Rikou in the hospital and aiding Hamazura's escapes. Her involvement includes Item's operations against groups like School. During the Battle Royale arc, she fought Kakine Teitoku and his subordinates, prioritizing Takitsubo and Hamazura's safety when Item's hideout was compromised. She later assisted Hamazura against Stephanie Gorgeouspalace and the Freshmen group, cementing her role as a key ally. Her development features adapting Offense Armor tactics against opponents manipulating nitrogen and maintaining defensive capabilities across diverse combat scenarios.