Saiai Kinuhata

Saiai Kinuhata is a supporting character from A Certain Magical Index, and its popular spin-off, A Certain Scientific Railgun. As an amalgamation of the two series, the franchise as a whole is referred to as "Raildex."

A Level 4 Esper from the futuristic Academy City, she is an operative of the organization known as I.T.E.M., alongside the likes of Shizuri Mugino, Rikou Takitsubo, and later, Shiage Hamazura. She occasionally comes across other notable characters of the franchise, including Mikoto Misaka.

It is unknown of what her whereabouts exactly were before the events of the Murder Game, though it can be assumed that she is from the same world and dimension as Accelerator, Touma Kamijou, and others, the world taking place during the DRAGON Arc at this point in time.

Right Hand of the Crimson Moon

She was a decently involved figure, befriending the likes of Ryan Duchannes, Frank Castle, Ilona, and Minato Arisato, among others, during the event.

Her relationships with Shizuri Mugino and Shiage Hamazura also became notable during the later chapters of the Murder Game, getting into a fight with the former and being able to snap the Level 5 Esper back to her senses and out of her furious hunt for Hamazura.

After exchanging goodbyes with Ryan Duchannes, she returned to Academy City in the epilogue along with Shiage Hamazura and Rikou Takitsubo in hopes of rebuilding the organization ITEM alongside their former leader, Shizuri Mugino.

Shiage Hamazura - A major protagonist of A Certain Magical Index who also debuted in Right Hand of the Crimson Moon. The two of them are friends and allies through their time within the organization ITEM, though Hamazura personally sees it more as a "victim and bully" relationship than anything else, though they do remain close either way and often enjoy watching C-movies together.
Shizuri Mugino - Another character from A Certain Magical Index who also made her debut in Right Hand of the Crimson Moon. Like Hamazura, Kinuhata is a member of ITEM before it was forcefully disbanded, and then became a member again upon its reinstation. As such, she is close allies and friends with him and Mugino.
Ryan Duchannes - A character from Caster Chronicles who also debuted in Right Hand of the Crimson Moon. The two of them became close friends over the course of the Murder Game. Despite them being around the same age, Ryan's naivety bounced well off Kinuhata's more blunt and brusque personality.

Saiai's first name can be translated as "beloved", while her surname Kinuhata means "silk flag".

Despite being a powerful esper, Saiai is one of the most mellowed-out characters in Item; she isn't a screw-up like Frenda, nor is she as frightful as her leader, Mugino. She enjoys C and B movies and likes to tease others, Shiage in particular because of his reaction to anything sexually suggestive. She is also described as being very eccentric. Despite this, she is still quite serious and dangerous during a mission, having a much more subdued mien than Mugino or Frenda, Item's other combatants. She is also described as obedient-looking, a contrast to her playful personality when out of missions.

She also likes to add "super" (超, chou) to her remarks. The Funimation subtitles translate chou as "ultra". It is likely due to her brain being inserted with Accelerator's thought patterns, who has a penchant in swearing, during the Dark May Project that this verbal tic may have arose, replacing an expletive with the word "super". This is somewhat backed up by the experiment modifying the subject's personality when inserting Accelerator's thought patterns. Moreover, it is backed up by Accelerator himself who noticed his manner of speaking with Kuroyoru Umidori, another subject in thought pattern modification in the Dark May Project.

Kinuhata Saiai's ability is known as Offense Armor (窒素装甲, Chisso Sōkō (Ofensu Āmā)?, lit. "Nitrogen Armor", Yen Press: Nitrogen Armor). At Level 4, the ability allows Saiai to control the nitrogen in the air in order to create a thin barrier around her.[61] It is the result of the horrific experimentation done to her in the Dark May Project, where a portion of Accelerator's thought patterns were inserted into her brain. Apparently originally an atmospheric control-type esper, this process allowed Saiai to gain a rapid increase in the strength in her powers, though at the cost of the stability of her personality. Here, Saiai received an idealized version of Accelerator's Redirection, and like Accelerator's this gives her the ability to create a barrier around her, though now instead uses super-compressed nitrogen instead, which is the primary function of her ability as defensive capability. Her power creates a barrier 360 degrees around her body, and also activates automatically without her wanting to. The armor is very effective, allowing for bullets from handguns to sniper bullets to be unable to penetrate her.

A secondary capability of her ability allows her to control compressed masses of nitrogen, allowing her to lift heavy objects like cars and deal powerful blows that can destroy entire walls. However, her effective range is very small as it only extends a few centimeters from her palm. She is also somewhat capable of manipulating air currents via displacing the nitrogen, which she uses for her Offense Armor. This is the method that allowed Saiai to confuse the man-eating cockroaches of Hisako, disrupting the scents that is used by Hisako to control them, and allowing her to make them turn on her.

A weakness of this ability is that a sufficiently powerful force can just knock her down due to her small body, as with the case against Sunazara Chimitsu's sniper rounds, and Umidori using thousands of Bomber Lances on her.

Saiai acknowledges the defensive limits of her Offense Armor later, where she is confronted with the sheer destructive power of Stephanie Gorgeouspalace's light machine shotgun. She notes that taking more than seven bullets at less than five meters of range would be "super bad". By the end of their fight Saiai incurs several injuries, though none are life-threatening. In order to compensate for foes who prove to be able to eliminate naturally-occurring nitrogen in the air like Stephanie, Saiai carries around a small canister of liquid nitrogen for use at all times.

Other abilities
She is a capable marksman, able to use handheld missiles to accurately target an enemy from a few hundred meters away while being shot, as well as shoot at a moving target accurately from a moving car.

Saiai is a girl with short brown hair in a bobcut.

In Toaru Majutsu no Index she wears a fluffy knit dress, a sweater dress to be exact. She wears no legwear other than striped socks, exposing her thighs and legs. According to Hamazura Shiage's assumption, Saiai may have calculated that the length of her sweater would expose enough of her thighs and legs but not to the point that her butt and panties will be exposed even if she were to bend over. Saiai later references the phenomenon while bending over, giving credence to Shiage's assumption.

In Toaru Kagaku no Railgun, she is seen more modestly, wearing an orange hoodie and hot pants.