Hibiki Tachibana (立花 響) serves as a central protagonist within the multimedia franchise. Her history stems from a traumatic incident two years before the main story: surviving a devastating Noise attack on a Zwei Wing concert, where she suffered near-fatal injuries. Singer Kanade Amō saved her life through sacrifice, embedding a fragment of her Gungnir relic within Hibiki's chest. This fragment granted Hibiki the latent potential for Symphogear powers. Following the attack, she endured extensive rehabilitation and received Special Disaster Compensation, but faced severe bullying and social isolation, falsely accused of murder and theft. This period included abandonment by her father, deepening emotional scars and leading her to suppress feelings behind forced optimism.

Initially, Hibiki's Symphogear abilities manifested incompletely due to the Gungnir fragment, resulting in limited armor coverage and a lack of conventional weapons. She relied on hand-to-hand combat augmented by piston-driven gauntlets amplifying her physical strikes, incorporating martial arts and explosive bursts of mobility. Intense emotional distress, particularly anger, could trigger unstable berserk states, causing relentless attacks while ignoring personal safety. Across multiple conflicts, her powers evolved: The Gungnir fragment began spreading through her body in the second season, threatening her life with each transformation. This crisis resolved when energy redirected from Miku Kohinata's Shénshòujìng purified her body, temporarily destroying her Symphogear. She later regained her powers by synchronizing with energy from Maria Cadenzavna Eve's Gungnir relic, acquiring new Armed Gears like jet-powered gauntlets and drills. Subsequent exposure to the Shénshòujìng's effects during a later conflict purged the Curse of Balal—a genetic restriction limiting human potential—from her body. This allowed her to fully harness Gungnir's nature as a divine weapon, earning the designation "God Slayer" and enabling the destruction of other divine artifacts.

Personality-wise, Hibiki presents as cheerful, optimistic, and deeply compassionate, often pursuing non-violent resolutions and extending empathy to former adversaries. This stems from internalizing Kanade's dying words to "never give up on living." However, this masks underlying trauma including survivor's guilt, fear of abandonment, and lingering effects of past bullying, causing her to hide vulnerability and avoid crying except before her closest friend Miku or family. Academically, she struggles with inattention and poor performance, worsened by her Symphogear duties, yet demonstrates unexpected tactical ingenuity in combat. Notable traits include emotional volatility when confronting broken promises, sacrifices, or criticisms of protectors, provoking intense fury; dramatic reactions to everyday situations, sometimes played for humor; and a pronounced love of food, particularly rice. Her relationships define key aspects of her journey: Miku Kohinata, her childhood friend and roommate, serves as her primary emotional anchor and motivator. Their bond endured testing when Miku temporarily became an adversary, resolved through Hibiki's unwavering belief in their connection. She views Tsubasa Kazanari as both a mentor and a link to understanding Kanade's legacy, eventually aiding Tsubasa's healing from trauma. Her empathy towards antagonists like Chris Yukine, Carol Malus Dienheim, and Saint-Germain often turned them into allies, reflecting her belief in redemption.

Her role culminates as a unifying force, symbolized by her unique ability to synchronize with other Symphogear users and redirect collective energy into combination attacks. This synergy, combined with her "God Slayer" capability, positioned her as pivotal in defeating existential threats like the Custodians. Her character arc concludes with a continued commitment to protecting others, embodying themes of resilience and connection forged through adversity.