Arisu Sakayanagi

Arisu Sakayanagi is the class representative of class 2-A.

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.

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.

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.

Plot
Arisu and Kōhei Katsuragi are being talked to by the student council president about the school system.

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

One day, while out in the rain she and her followers meet Kakeru Ryūen and his gang. While her group prepares for a fight, she stops them, though stating to Kakeru who remarked on how it looked like that she established her rule in the school very quickly. He swore to her that he will take down all the classes including hers so that he could rule the school. She simply smiled at his declaration, remarking how he is making things interesting for her, before agreeing with his previous statement.

Abilities
Along with Kōhei Katsuragi, Arisu leads class 1-A and has a group of followers that do everything she orders. Despite her limited physical ability due to heart defects, Arisu is notable for her talents as being the only person Katsuragi reports to, despite his own academic prowess and leadership skills.

She is shown to be resourceful when she was unable to go on the school cruise, as 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 as Manabu Horikita, the current Student Council president at that time, praised her grades in the recent midterms. This was notable, as the only person he had been seen complimenting was Kiyotaka, who is extremely intelligent and skilled in manipulating his academic ability in his own right.

Intellectual Abilities
Arisu is known for her vast intelligence, which even gained praise from many people of other classes such as Honami Ichinose, the representative of class 1-B who reported to her teacher Chie Hoshinomiya that Arisu is someone to watch out for.

Etymology

 * The name Arisu means "exist" (有) (ari) and "tree" (栖) (su).
 * Arisu's surname Sakayanagi means "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.
 * 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.'