Hibiki Kennou enters the narrative as a physically imposing delinquent with a rugged demeanor and a dangerous gleam in her eye, reflecting her street-smart background and reliance on fighting for survival. She has long blonde hair and stands slightly taller than average. Growing up in state care after her mother's death from an illness, she rebelled against her maternal grandfather's restrictive environment during a failed adoption attempt, leading to legal troubles and estrangement. She deliberately avoids contact with her grandfather and lives independently, often evading authorities.

Hibiki shares a childhood connection with Hiroshi Karigari, recalling an incident where he protected her from a feral dog by pushing her down to avoid detection. Upon reentering Hiroshi's life, she discovers his creation of an android modeled after his crush, Marie. Hibiki blackmails him, threatening to expose the android unless he becomes her boyfriend. This conflict stems from her unresolved romantic feelings for Hiroshi and resentment over his affection for both the human Marie and the android, whom she derisively labels "My Dear Marie." Viewing the android as a rival, Hibiki feels intimidated by its perceived moral superiority and frustrated by Hiroshi's defense of it. Her aggression escalates to physical confrontations, including a near-even fight with the android Marie.

Her personality combines anger, impulsiveness, and a capacity for manipulation; she employs tactics like getting Hiroshi intoxicated to facilitate non-consensual advances, though framed comically. Despite her tough exterior, she struggles with vulnerability regarding Hiroshi's rejection and her sense of abandonment. In combat, Hibiki utilizes street-honed fighting skills and specialized techniques: the "Phantom Fist" (a punch misaligned with her visual trajectory), the "Whirlwind Attack" (a rapid flurry of kicks and punches), and an unnamed ki attack that temporarily drains her energy. She harbors a strong dislike for guard dogs due to negative past experiences. Hibiki departs after failing to sever Hiroshi's bond with the android, her lingering feelings for him unresolved; the narrative does not revisit her storyline after her departure.