Tatenashi Katana Sarashiki (更識 楯無, Sarashiki Katana Tatenashi) is the Student Council President of the IS Academy.
Tatenashi has short light blue hair, dark red eyes and a voluptuous figure, with slender thighs, a narrow waist and large breasts. Her IS Academy uniform consists of the typical white and red blouse, a skirt that is short compared to others, with a yellow tie, and a pale green overcoat around it, along with red leggings.
She is also known to dress scantily in front of Ichika just to see his reactions, which she finds 'cute' (e.g wearing only panties with a simple white shirt or a 'naked apron' although she did wear a swimsuit underneath).
She usually has blue fans with her that display kanji that indicate what she is going to do or what she is talking about. Her IS suit is dark blue.
In the light novel, she is said to have very high standards due to her prestigious family, where everything must be done perfectly. Despite that, she has, as Ichika puts it, "a wild or rather whimsical personality with slight cat-like mischief." She enjoys teasing people (her unfortunate victims are mostly Ichika and Laura). Despite her tendency to tease others, Tatenashi has also shown moments of being flustered, mostly as a result of her feelings for Ichika.
She is very charismatic and a natural leader, easily earning the respect from most of the students at the academy. She even got the normally difficult Houki to become friendly with her after a short while, which surprised Ichika.
Her teasing includes appearing before Ichika half naked or even asking him if she should undress herself. She often does both when she has him give her a massage, after which she teases him about him enjoying it. Tatenashi also teased Houki about how Houki's breasts were slightly bigger than her own. She seem to have stopped teasing Ichika on the subject, ever since she realized her feelings for him. She even gets clearly angry with him whenever she sees him looking at other girls' bodies. She still enjoys teasing girls on the subject and putting them in embarrassing situations, such as the Live Cosplay Changing Race.
She does have a serious side, though she tends to talk playfully even when serious, so it can be difficult to determine just how seriously she is taking things. Tatenashi takes failing rather hard, due to the fact she has many titles and positions (Student Council President, Sarashiki family head, and IS Representative of Russia).
She is also a little insecure when it comes to her sister, as she wants to help/support her, but they do not get along with each other, due to their competitive natures - a holdover from their childhood. This is one of the few topics where she shows a gloomy side instead of her normal cheerfulness.
Despite all of the advances she made on Ichika, and joking she could fall in love with him (which ends up happening), Tatenashi is actually quite innocent when it comes to being in love herself. Having never been in love before, she found herself being unable to control her new found feelings. This resulted in her becoming very nervous and overly-conscious around Ichika, displaying none of her usual confidence or playfulness that she would before. This sudden change made it easy for others to notice her new found love for Ichika.
- Kanzashi Sarashiki - Her younger sister. Tatenashi loves her sister but has trouble communicating with her due to their different personalities, making it look like they do not get along well with each other, and she usually only talks to her when it's necessary. Nevertheless, the two sisters do care about each other, as Tatenashi didn't hesitate to use her body (even when she was already injured) to protect her younger sister. They finally resolve their differences at the end of Volume 7. Well their relationships had improved since then, Kanzashi started seeing her older sister as a love rival after noticing Tatenashi's feelings for Ichika (ironic since it was thanks to Ichika that they finally managed to get along).
- Ichika Orimura - She was assigned by the headmaster to protect him and prevent his IS from being stolen. She enjoys teasing or flirting with him in a manner that makes him very uncomfortable. Throughout Volume 6 it is shown that she is becoming more mindful of Ichika, even thinking of him on random occasions. In Volume 7, she trusted him enough to ask him to help her little sister, Kanzashi. She later questioned her reasons for doing so before admitting to herself that she wanted to flirt with him. At the end of Volume 8, her feelings for Ichika take a step further when she reveals her true name (Katana Sarashiki) to him, which has a special significance in the Sarashiki family, indicating that a certain level of affection has grown between them (at least from her side). Afterwards, their relationship started changing with Tatenashi becoming more shy around Ichika, while Ichika on the other hand started becoming more comfortable around her. The other girls (including Kanzashi) even worried if the two them were dating each other. While both of them denied this claim, Ichika did admit that he enjoys being with Tatenashi, even pointing out her positive traits compared to the other six girls. Tatenashi even started thinking about having Ichika marry her someday.
- Houki Shinonono - Tatenashi asked Houki to be her partner during a tournament at the IS Academy. Tatenashi starts to develop an interest in Houki due to the fact that they both have sisters they cannot understand (Tabane and Kanzashi). Houki seems to act more respectful to Tatenashi than others and doesn't fight back like she would with the girls in her class, something Houki questioned herself about. Tatenashi is fond of teasing Houki about the size of her bust. However, Houki doesn't like it when Ichika gives Tatenashi better treatment because she is a senior and worried if the two were dating.
- Utsuho Nohotoke - Utsuho is Tatenashi's personal maid and a member of the student council.
- Kaoruko Mayuzumi - Tatenashi gets along with Kaoruko since the two are in the same year and have similar personalities. Tatenashi respects Kaoruko knowledge enough that she got help from her in finishing her IS. However, she didn't like when Kaoruko teased her about acting like a married couple with Ichika.
- Squall Meusel - The two are enemies. This is due to the fact that Squall is a squad leader in Phantom Task and the Sarashiki family has been trying to stop them. During Volume 6, Tatenashi found her watching the chaos M was causing from a safe distance away. This may suggest the two have a least encounter each other before.
Infinite Stratos & AbilitiesEdit
As the head of a secret organization and the current IS Representative of Russia, she is implied to be exceptionally skilled in many areas related to IS and other skills related to fighting. She's been consider a prodigy even by her family standards ever since she was a child. She is known to be talented in judo, as she knocked Ichika out during their first fight (Ichika stopped counting and passed out after being thrown around 9 times). She apparently has developed a knack for unlocking Ichika's room lock (much to his chagrin). Outside of her combat skills, she is very cunning and intelligent in many fields. She usually puts her wits to work by managing the students at IS Academy while keeping Ichika close to her. She likewise said to be very skilled at almost everything she does, including cooking.
Furthermore, the title of the President of Student Council goes to the most proficient student, thus explaining why she is the SC President even though she is a second year student. She has more than once defended her right to the position by easily defeating any of the other personal IS pilots at the Academy. However, her overconfident in being the strongest student at the academy can cause her to leave herself open to dangers and counter attack, and as a result has gotten injured when she could have avoided it by being more careful.
Her personal IS is the 3rd Generation Type, Mysterious Lady. The Mysterious Lady's exoskeleton is mostly parts of the leg, with only a few parts above the waist. It uses a large lance, and controls a special type of water that can charge the lance with power, create a fake, block strong attacks, turn into mist and explode.
In the Light Novel, she is the 39th leader of the Sarashiki family. Behind the cover of a traditional family with a long history, it's actually a secret organization fighting against another secret organization known as Phantom Task. It is revealed that her name, Tatenashi, is not her real name. It is family tradition that the eldest sibling of the Sarashiki family must replace his/her name with Tatenashi when he/she becomes head of the family. At the final part of Volume 8, she reveals her true/former name to Ichika: Katana.
She is seen standing on a building, claiming that it is time for her to make her moves, while looking at Ichika from afar.
She first appeared behind Ichika to tease him before disappearing from his sight. Later during the introduction speech for the cultural festival, she introduced the "Every Club Fight For Orimura Ichika War" to get him to forcefully join the number one club and to make the girls motivated to do their best.
- "Welcome back. Do you want dinner, a bath, or... do.. you.. want.. me?"- Tatenashi to Ichika.
- "P-Please...do perverted things to me too..."-Tatenashi to Ichika.
- She holds the unofficial record of making Ichika get a nosebleed when she makes him massage her. Ironically, after falling for him herself, Tatenashi end up having nosebleeds when she imagined being in a relationship with Ichika.
- Tatenashi is Ichika's third female roommate in Room 1025.
- In the Light Novel and World-Purge OVA, she revealed her real name to be "Katana" to Ichika. Stating that the eldest child and head of the Sarashiki family must take the name 'Tatenashi'. Her real name is not suppose to be known to anyone but her family and that telling it to someone of the opposite sex is consider a sign of affection in her family. Because of this, she began thinking of making Ichika marry her someday after remember this.
- Tatenashi has many similarities to Tabane: Both are respected geniuses in their fields, both are very cheerful and playful and somewhat lecherous. Both of them have younger sisters whom they love and care about but who feel inferior to their elders and started to avoid them as a result (this problem has been solve in Tatenashi's case). The main difference between the two is that Tatenashi has no problem talking to and being with to other people while Tabane doesn't really care about many people.
- Outside the IS universe, Tatenashi is extremely similar to Chō'un Shiryū from Koihime†Musō in both physical appearance and personality (both have short light-blue hair, red-shade eyes; both are top-tier fighters—both are lancers, as a matter of fact—with intellect to match; and both are always calm, playful, and often quite perverted). It is possible that Tatenashi is based on Chō'un, as IS came out 2 years after the release of Koihime.
- She has a similar appearance to Sen Yarizui from "Ben-To."
- She also has a similar appearance to Ruka Suirenji from Hayate no Gotoku.
- She has the same birthday with Chifuyu Orimura