Hatsuho Shinonome was born on September 9, 1923, in Tokyo's Shitamachi district, where her family serves as caretakers of the historic Shinonome Shrine. Growing up as a shrine keeper's daughter, she developed a deep connection to local traditions and festivals. Her childhood friendship with Sakura Amamiya began during Sakura's annual visits when her father delivered swords to the shrine; they bonded beneath the shrine's Thousand Year Cherry Blossom tree. This friendship fractured after an argument while attempting to imitate ceremonial dances, and they lost contact when Sakura's visits stopped. Years later, Hatsuho joined the Imperial Combat Revue's Flower Division during its decline after the Great Demon War. She considered quitting until Sakura joined the team, rekindling their friendship and strengthening her commitment to the Revue.

Personality-wise, Hatsuho embodies the passionate Shitamachi spirit, fiercely devoted to her hometown, festivals, and community. She speaks with directness and possesses a fiery temper, often resolving disputes through physical confrontation. Despite her rough exterior, she acts as a reliable mediator within the Flower Division, balancing her combat role with providing emotional grounding for teammates. She harbors deep insecurities about her value to the team, especially after new members like Anastasia Palma joined and Sakura became acting captain, leading to jealousy and reckless behavior in battle. Her loyalty remains unwavering, though she struggles with a fear of heights and masks work-related arm injuries with bandages.

In combat, Hatsuho pilots a crimson Mugen mech, wielding a rocket-propelled warhammer for powerful area-clearing attacks. She initially used a modified Kobu unit before transitioning to the Mugen after early missions. Key battles include defending Tokyo against demon incursions and confronting antagonists like Yasha. During the final battle against Yasha, Hatsuho sacrificed herself to weaken the enemy after witnessing teammates' deaths, delivering a defiant speech about their bonds before perishing. She was later revived by spiritual cherry blossoms conjured by Sakura Shinguji.

Hatsuho's character development emerges through relationships. Her reconciliation with Sakura involved a physical fight where Hatsuho challenged Sakura's self-pity, symbolizing their enduring bond. She supported Klara M. Ruzhkova, encouraging her integration into the team. When chosen as deputy captain, she undertook a festival date with Seijuro Kamiyama, wearing a kimono and sharing a kiss during fireworks—a contrast to her usual tomboyishness. Her journey resolves initial insecurities as she accepts her role as both combatant and unifying force within the Flower Division.