Ichika, an Iga clan fighter, was assigned by Abraham, a Catholic priest, to act as caretaker for the infant Saki. Abraham intended to exploit Saki's innate supernatural abilities for his European conquest. Ichika, however, developed genuine maternal affection for the child and defied Abraham, escaping with Saki to rescue her. They settled in a remote village where Ichika posed as Saki's mother, working as a bar singer to support them. When Saki began exhibiting signs of a mysterious illness—later manifestations of her powers—Ichika sought out Dr. Morisuke, reputed to treat such abilities. Ichika carried a necklace pendant bearing the Iga clan crest, hinting at past connections. Needing to travel north to reach Morisuke, Ichika requested passage from Yasuke, a local boatman and former samurai. He initially refused due to dangers. Undeterred, Ichika embarked with Saki alone. Yasuke later relented and joined them. During their boat journey, mercenaries hired by Abraham ambushed them. In the ensuing battle, Ichika intervened to protect Yasuke from an attack by the mercenary Nikita. This left her vulnerable, and she was struck by energy blasts from another mercenary, Haruto, causing the severe injury and loss of her left arm. This trauma triggered a massive uncontrolled release of Saki's powers, incapacitating everyone. Following the attack, Ichika disappeared and was presumed dead. Her sacrifice profoundly impacted Saki and Yasuke. Saki later returned to their village and gave Ichika's Iga clan necklace to Yasuke, signifying Ichika's wish for him to have it and Saki's acceptance of her loss. Yasuke attached the necklace to a new sword, symbolizing a connection to Ichika's memory and his own path. Her actions, from rescuing Saki to her final protective act, defined her as a devoted adoptive mother who prioritized Saki's safety above her own life.