Arisu Sakayanagi

Appearance
Arisu is a petite teenage girl with lilac colored hair and violet eyes. She wears a black beret on her head with a gray ribbon connected to it and wears the standard school uniform.

She often walks with a cane due to her health condition and she is quite short for her age when comparing to other classmates due to her at birth.

Personality
Arisu appears to possess a "go with the flow" attitude as she accepts most situations with no protest. Although she voices her dislike of boring situations after Kōhei Katsuragi (Arisu's classmate) spoke about the class scores. Unlike Katsuragi, who has a conservative stance, Arisu possesses an innovative outlook on things. Together, the pair effectively lead class A through the school years. In the eyes of her schoolmates, she is considered to be someone who stands out from the rest and that no one has ever seen her lose her composure. Truthfully, she is just like any normal girl and the only one who was allowed and seen her act that way was Kiyotaka Ayanokōji.

She enjoys situations she finds interesting as shown when she smiled at Kakeru Ryūen's declaration to rule the school or when she listened to the speech of Suzune Horikita.

In the light novels, Arisu enjoys toying with people, as seen when she cryptically hinted that she knew Kiyotaka Ayanokōji, whereas he doesn't remember meeting her before. Later on, while being together with Honami Ichinose, she also appeared to be very confident and complacent after Teruhiko Yukimura of Ayanokōji Group boldly claimed that D-Class has a plan to overtake A-Class soon. She always carries an aura of imperturbability and seems like a wiseacre whenever anyone is in her presence although her tone could effortlessly make people feel comfortable around her.

Additionally, although she has an easygoing personality, it was shown in the latter part of the series that she is easily provoked when being described based on her petite appearance (e.g. "Little Girl"), as she believes that it does not give her justice, due to her domineering qualities. She may come off as egotistical and arrogant towards onlookers, however this is also a frequent use of one of her tactic to establish control over the minds of those she chosen. She blatantly told Ichika Amasawa that she doesn’t view her as a threat and that she views her as a failure when compared to Kiyotaka. The latter successfully recognises that she is trying to agitate her and retaliated by accepting her challenge before walking around. In truth, Arisu finds her extremely dangerous and couldn’t afford to allow her to run free which prompted her to reign her in before she does something detrimental.

Plot
Arisu is introduced in the anime when she and Kōhei Katsuragi were being talked to by the Student Council President about the school system.

After a while, she is seen next to Katsuragi in the hallway while observing the class points for each class. She then proceeded by commenting on how things gets very boring due to seemingly no struggle between the groups.

One day, while out in the rain she and her followers met Kakeru Ryūen and his followers. While her group protectively surrounds her, she stops them. Ryūen then remarked on how it looked like that she had established her rule in the school very quickly and only in a manner of weeks. He swore to her that he will take down all the classes including hers at the end so that he would be the one to rule the school. She simply smiled at his declaration, sardonically remarking of how he was going to make things fun and interesting for her, before agreeing with his previous statement of her accomplishment.

Abilities
Along with Kōhei Katsuragi, Arisu leads class 1-A and has a loyal group of followers that would faithfully do everything she orders. Despite her limited physical ability due to birth defects, Arisu is notable for her talents as being the only person Katsuragi reports to, despite his own outstanding academic prowess and leadership skills. Manabu Horikita the former student council president even praised her phenomenal holistic management of her class, such as being able to stand out from the rest of the classes in terms of class points despite only having a handful of weeks to establish her control, and personally invited her for a chat to commend her achievements.

She is also shown to be resourceful as when she was unable to go on the school cruise, she had Masumi Kamuro conduct research on certain students and Masayoshi Hashimoto to physically manifest her plans in her stead.

Academic Abilities
Arisu is known for receiving great scores throughout her school-year and has the highest overall score for her year in the OAA. Even Manabu Horikita, the previous Student Council president at that time who has extremely high standards, praised her grades in the recent midterms. This was notable, as the only other person he had ever been seen complimenting was Kiyotaka Ayanokōji, who is extremely intelligent and skilled in manipulating his academic ability in his own right. She easily boast one of the highest academic and adaptability grades in the entire school's history.

Intellectual Abilities
Arisu is known for her vast intelligence, which even garnered praises from many people from other classes such as Honami Ichinose, the representative of class 1-B who reported to her teacher Chie Hoshinomiya that Arisu is someone they had to actively watch out for. She is also very manipulative, cunning and perspicacious in her plans which can only be rivalled by Kiyotaka, by playing to the strength of her allies while targeting the weaknesses of her enemies. For instance, she was able to emotionally scar Honami the leader of Class 1-B by revealing her secret, effectively taking out the leader of the second best class and their chances of competing with her. Additionally, she played Honami to her advantage by exploiting Honami's kind and forgiving nature by forming an alliance with them before other classes could. She is also very good in chess, perfectly capable to be on the national level and even cause difficulty for Kiyotaka who was trained from young to be good in it. She is easily able to factor in her opponent's idiosyncratic thought processes in her plans, thinking more than 10 steps ahead of them and countering them in the span of seconds. Her deduction and analytical skills are most likely the highest in the entire school and on par with Kiyotaka when he is serious. She is easily able to lead and have dominion over most of her classmates in Class 1-A who are full of distinguished students and individualistic personalities and have them obey her.

Name Etymology

 * The name Arisu consists of kanjis that mean "exist" (有) (ari) and "tree" (栖) (su).
 * Arisu's surname Sakayanagi consists of kanjis that mean "slope" (坂) (saka) and "willow" (柳) (yanagi).

Trivia

 * In the light novel, Arisu debuts in Volume 5; however, in the anime, she first appears in Episode 1, which chronologically takes place much sooner than the light novels.
 * Arisu ranks #21 in the "Female Character" category in the 2021 edition of 's  guidebook.
 * For the 2nd Year arc, when asked about her aspirations for the next year, she answered  'To lead a school life that's interesting... And protect my beloved person from unwanted vermin I suppose.'