Habara earned the moniker "Archdemon" at East Yada Elementary School through aggressive bullying and violent behavior, terrorizing other children. She inflicted a permanent forehead scar on Karasawa. Her reign concluded only after a battle against ten of the school's strongest warriors, including Yanagin and Rubber Shooter (later identified as Yoshitake Tanaka), ended in a draw. This confrontation initiated her transformation, leading Yanagin to monitor her and eventually form a friendship.

Now a polite and reserved second-year student at Sanada West High, Habara maintains a close friendship with Yanagin and Ikushima, the trio known as the Funky High School Girls. She acts as the group's straight man, reacting with dismay to their antics. Habara remains deeply insecure about her flat chest and becomes emotional when her violent past surfaces. Her appearance contrasts sharply with her elementary school days: light brown hair in a neat bob and standard uniform replace long, spiked dark brown hair and frayed clothing.

Habara retains extraordinary physical abilities from her past, including immense strength and heightened reflexes, demonstrated by destroying a ball during play and damaging a punching machine with her fingers. These traits occasionally surface when threatened, though she consciously suppresses her "Archdemon" persona. Her relationship with Karasawa remains strained due to his lingering childhood fear. She misinterprets his nervousness as romantic interest, developing feelings for him. The scar she inflicted serves as a painful reminder, driving her quest for atonement.

A significant shift occurs when Habara saves Karasawa from a dangerous fall, sustaining a head injury. Believing this act compensates for the scar, her personality changes noticeably: she laughs confidently in his presence, signaling the re-emergence of her Archdemon self. Her friends observe this change, with Ikushima confirming the persona's return during a hospital visit after the rescue.