Keiko serves as a dedicated schoolteacher in Hope Town, a settlement forged by survivors in the post-apocalyptic wasteland after the Great Kanto Hellquake. She continues teaching children fundamental subjects like grammar and arithmetic despite the harsh environment, demonstrating her commitment to preserving humanity's knowledge. Her compassion extends beyond lessons, evident when she gifts seeds to her student Saburo Tenma and nurtures his growth.

Saburo develops romantic feelings for Keiko, fueling his protective instincts toward her and Hope Town. When the Hell's Wind biker gang assaults the settlement, Keiko hides with Saburo's parents. The gang captures her, subjects her to physical and sexual assault, and attempts to strip her before Violence Jack intervenes and rescues her. Following this trauma, she remains with Saburo and his family for several years, providing stability.

Later, a samurai intruder attacks Keiko's classroom, disrobes her, and assaults her. Saburo, now an adult, intervenes and kills the assailant, discovering the attacker was sent by the Slum King. Subsequently, another assailant assaults Keiko and forcibly tattoos her body. Saburo retaliates again, but both suffer fatal gunshot wounds during the confrontation. Though supernatural intervention revives Saburo to defeat their attackers, Keiko succumbs to her injuries and dies.