Arisu Sakayanagi

Age: 16
Birthday: March 12
Height: 150 cm
Measurements: B70/W54/H77

She normally keeps her thoughts to herself and accepts most situations with no protest, though she voices her dislike of boring situations. Unlike Kouhei Katsuragi, who has a conservative stance, Arisu possesses an innovative attitude. The two each lead separate factions within Class A, though the majority of the class submit to Arisu.

She was mentioned to know Kiyotaka Ayanokouji and his past in the novel. This makes her the first person to know about Ayanokouji's mysterious past.
(Source: You-Zitsu Wikia)