Rin, [Yumi Sugimoto], a shy and awkward high school student who is constantly bullied, begins to feel something shift inside her when a sudden, sharp pain shoots through her hand during another cruel incident. Soon she learns she is a descendant of the ancient Hiruko clan, a lineage of mutants with extraordinary powers. Before she can fully grasp what this means, anti-Hiruko soldiers storm her home, and Rin’s world erupts in violence: her parents are killed, and Rin barely escapes with her life. Her father, [Kanji Tsuda], is among the fallen, a brutal reminder of the cost of power and fear. In the chaos that follows, Rin loses more than she can bear and lashes out in a grief-fueled rampage, destroying an entire shopping district as misunderstanding and rage drive her actions.
Rin’s path intersects with Rei, [Yuko Takayama], another mutant who has wandered far from any normal life. Rei introduces Rin to a small, rag-tag group of rebels led by a striking figure, Kisaragi, [Tak Sakaguchi], a transvestite samurai who is determined to restore the Hiruko clan’s place in the world. Under their guidance, Rin begins a grueling period of training, wearing an iron mask to learn to control her burgeoning powers. During this intense period, Yoshie, [Suzuka Morita], a tentacle-armed Hiruko survivor, reveals Rei’s past: three years earlier Rei had been a freak show attraction, and the only person who showed her kindness was a human boy who gave her a gold cross necklace. Rin later discovers that necklace herself, finding it after Rei accidentally drops it during a training session, a small beacon of memory in a world of violence.
When Rin finally gains control over her abilities much sooner than Kisaragi expects, he assigns her and Yoshie to infiltrate an anti-Hiruko conference and strike down a high-ranking general named Koshimizu. The mission goes through with surprising efficiency: Rin and Yoshie disable Koshimizu, but the pair hesitate at the sight of innocent survivors still alive. Rei, acting on Kisaragi’s orders, eliminates the survivors, underscoring the brutal moral ambiguity that threads through their cause.
Despite the ruthlessness surrounding them, Rin comes to a crucial realization: she cannot fully abandon her human side. This turning point leads her to persuade Yoshie to join in protecting ordinary people rather than subjugating them. Meanwhile, a disturbing program unfolds as other Hiruko schoolgirls are brainwashed to carry out suicide bombings at various locations, a grim reminder of the manipulation at the heart of their struggle. In a chilling turn, Kisaragi kidnaps and drains the blood of the fervently anti-Hiruko prime minister, granting himself a grotesque, super-powered body that amplifies his threat.
Yoshie steps in to confront the brainwashed cadets, while Rin faces Rei in a confrontation charged with memory and emotion. A pivotal moment arrives when Rin returns Rei’s treasured gold cross necklace, which rekindles memories of the human boy who loved her and softens Rei’s resolve toward violence. This emotional catalyst helps pivot Rei away from unyielding war against humans. United by shared purpose, Rin, Rei, and Yoshie join forces to take down Kisaragi and to rescue the prime minister, offering a fragile hope that humanity and Hiruko can find a path to coexistence rather than annihilation.
