Sarashiki Tatenashi♀

Tatenashi is a 2nd year student at the IS Academy, Student Council President of the IS Academy, and the IS Representative of Russia; this is due her combat skills, which exceed Cadet level. 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 and tickling others (her unfortunate victims are mostly Ichika and Laura). Despite her tendency to tease, Tatenashi has also shown moments of being flustered, mostly as a result of her feelings for Ichika. 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 that she always prides herself in (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 topic where she show a gloomy side to her normal cheerfulness.

[From IS Wiki]