Tatenashi Sarashiki is known for her charismatic presence and unpredictable nature. As the eldest daughter of the esteemed Sarashiki family, she was raised with high expectations and an emphasis on perfection. Despite her prestigious upbringing, she exhibits a carefree and whimsical behavior, often described by Ichika Orimura as mischievous and feline in nature. Tatenashi frequently teases those around her particularly Ichika, her younger sister Kanzashi, and Laura Bodewig displaying a playful and occasionally provocative sense of humor.

Her mischievous behavior extends even into combat, where she often toys with opponents to observe their reactions upon realizing they’ve been outmatched. This habit can make her appear villainous, though it is typically driven more by curiosity and confidence than malice. Despite this lighthearted façade, she is capable of being flustered, particularly when confronted by her developing romantic feelings for Ichika.

Tatenashi’s leadership skills are widely recognized at the IS Academy. Her natural charisma and social tact allow her to quickly gain the respect of both students and staff. Even Houki Shinonono, known for her guarded nature, becomes friendly with her shortly after they meet something that surprises Ichika.

Her teasing often takes the form of suggestive remarks or behavior, such as appearing half-dressed in front of Ichika or jokingly inviting him to undress her during massages. Although she initially used this flirtation purely for amusement, her attitude shifts once she becomes aware of her feelings for him. At that point, she grows more sensitive to his interactions with other girls and expresses visible jealousy when he pays attention to them. While she continues to engage in playful flirtation, her actions become more sincere and emotionally driven.

Tatenashi maintains a composed exterior even in serious situations, often speaking playfully regardless of the gravity of the moment, which can make it difficult to discern her true intentions. As someone who holds multiple roles including Student Council President, head of the Sarashiki family, and Russia’s IS Representative Candidate she places considerable pressure on herself to succeed and views failure as a personal shortcoming.

One of the few areas where her cheerful attitude falters is in her relationship with her younger sister, Kanzashi. Their bond is strained due to their competitive natures and childhood rivalry. Tatenashi wishes to support her sister but struggles to connect with her. It is only after the events involving the Golem III incident that she begins to reconcile with Kanzashi, allowing them to grow closer.

Despite her confident and seductive behavior, Tatenashi is inexperienced when it comes to romantic love. Her affection for Ichika leaves her unusually nervous and self-conscious, a stark contrast to her usual boldness. Over time, she learns to manage her feelings more openly, returning to her flirtatious ways this time with genuine intent and often positions herself ahead of the other girls in vying for Ichika’s attention.

Tatenashi Sarashiki is a striking young woman with an elegant yet athletic build. She has short blue hair, styled with V-shaped bangs, pale skin, and sharp dark red eyes. Her figure is notably mature for her age, possessing a well-toned physique with slender limbs and a curvaceous silhouette. Among the female cast, she is often regarded as one of the most physically attractive, a point occasionally acknowledged by other characters, including Ichika Orimura, who has described her appearance as exceptional.

Her standard IS Academy uniform is a customized version of the typical attire. It consists of the academy’s signature white and red blouse, a yellow tie, and a shorter-than-usual skirt. She adds a pale green, sleeveless overcoat to her outfit and pairs it with red leggings, giving her uniform a more distinctive and personal flair.

In line with her teasing personality, Tatenashi occasionally wears revealing clothing around Ichika, often as a means of provoking or flustering him. Examples include wearing a loose white shirt over minimal attire or donning a “naked apron” outfit though she usually has a swimsuit or undergarments on underneath. These actions are typically played for comedic effect and align with her flirtatious, playful behavior.

One of her most recognizable accessories is a pair of blue folding fans, which she frequently uses to punctuate her actions or statements. These fans are often adorned with kanji characters that reflect her mood or intentions, adding to her theatrical and confident presence. During combat, Tatenashi wears a dark blue version of the standard IS pilot suit, matching her personal color theme.

In the Infinite Stratos light novel series, Tatenashi Sarashiki is revealed to be the 39th head of the prestigious Sarashiki family. While publicly recognized as a traditional household with deep historical roots, the Sarashiki family secretly operates as an underground organization engaged in covert operations. Their primary mission involves combating Phantom Task, a rival clandestine group with antagonistic motives.

Due to longstanding family tradition, the eldest child of the Sarashiki lineage is required to relinquish their birth name upon assuming leadership and adopt the title “Tatenashi”, a symbolic gesture representing their role and responsibilities as the family’s leader. As such, her real name is not initially known to others.

This detail is later revealed in Volume 8 of the light novel, during a moment of personal vulnerability. At the end of the volume, Tatenashi confides in Ichika Orimura and discloses her true given name: Katana Sarashiki.

Tatenashi Sarashiki is widely regarded as one of the most talented and versatile students at the IS Academy. As the designated IS Representative Candidate of Russia and heir to the Sarashiki family, a covert organization engaged in global conflict she possesses exceptional proficiency in combat, tactics, and leadership. Considered a prodigy from a young age, she has mastered multiple martial arts disciplines, including Karate, Judo, Taekwondo, Capoeira, and various armed combat styles. Her agility and precision in close-quarters combat have allowed her to easily counter skilled opponents such as Laura Bodewig and Houki Shinonono.

Tatenashi’s physical abilities are extraordinary, even among elite IS pilots. She demonstrates superior reflexes, strength, and durability. In the World Purge-hen OVA, she is shown evading coordinated gunfire from multiple opponents with ease. Her endurance is equally impressive; during the Golem III incident, she withstood a point-blank explosion after her IS armor was disabled, a feat that shocked both Houki and Kanzashi, the latter briefly believing she had died. Even after receiving a direct sword strike to the back without armor, she remained conscious until the end of the battle.

She is also a highly skilled swimmer and acrobat. In one instance, she swam several kilometers to infiltrate an American vessel suspected of harboring Phantom Task intelligence, doing so with no visible signs of exhaustion contrasting sharply with Ichika, who was visibly fatigued. Her athleticism extends to acrobatics, gymnastics, and tactical evasion techniques, often using flips and rolls in battle scenarios.

Beyond combat, Tatenashi is highly intelligent and capable in a range of non-combat skills. She is a gifted strategist and administrator, effectively managing student affairs as the Student Council President. The title itself is only awarded to the most competent student, a distinction she has defended multiple times by besting other Representative Candidates in combat. In addition, she has demonstrated impressive technical aptitude, such as quickly hacking into a military database to access classified information on Squall Meusel. Her culinary skills are also notable Ichika, an accomplished cook himself, has openly admitted that her cooking surpasses his own.

Despite her overwhelming talent, Tatenashi is not without flaws. Her confidence in her abilities can sometimes lead her to underestimate opponents or expose herself to unnecessary risk, resulting in injuries that could have been avoided with more caution.

Tatenashi’s personal IS is the Mysterious Lady (ミステリアス・レイディ, Misuteriasu Reidi), a third-generation unit with a unique aquatic theme. The unit features partial armor coverage, focusing primarily on the legs, while the upper body remains minimally protected. Its most distinctive feature is a set of floating crystalline objects known as Aqua Crystals, which generate water-based barriers that act as a fluid shield. These can be manipulated to absorb damage, obscure her position, or explode on command. The unit’s primary weapon is a large lance capable of channeling water energy, used to enhance offense or create deceptive illusions during combat. The IS was formerly known as “Gustoi Touman Moskwa,” roughly translated as “Moscow’s Deep Mist.”

The name Tatenashi (楯無) is written with the kanji for “shield” (楯, tate) and “nothing” or “without” (無, nashi), which together can be interpreted as “without a shield” or “no shield.” This name likely symbolizes her fearless and offensive combat style, as well as her tendency to fight with minimal armor through her IS unit, Mysterious Lady. It may also reflect her confident personality and willingness to take risks.

Her family name, Sarashiki (更識), combines the kanji for “renewal” or “change” (更, sara/kou) and “knowledge” or “awareness” (識, shiki), possibly suggesting a lineage associated with adaptability, intelligence, or transformation—traits that align with the Sarashiki family’s secretive and strategic role in the series.

Her birth name, Katana (刀奈), uses the kanji for “sword” (刀, katana) and a phonetic component (奈, na), reinforcing the martial theme associated with her character and family tradition.