A first-year high school student at Yuigaoka (3rd generation). Appearance: Mint green hair and pink eyes. Height: 163cm. Blood type: O. Birthday: December 28th. Personality: A cool-headed perfectionist. Stubborn and not the type to acknowledge others easily. Has an older sister, Natsumi Onitsuka. Commutes from Ushiku to Yuigaoka in Tokyo with her sister Natsumi. Calls Natsumi 'Ane-ja'. Uses polite language (honorifics) with everyone. Addresses her crush, Margarete, peers, and underclassmen without honorifics. Addresses upperclassmen as 'Senpai'. When with someone she loves, she drops the act, speaks casually, and acts spoiled.