Aya Isshiki plays Natsumi Kiryu, a tough and independent female detective working for the International Security Organization. Known for her bold, tomboyish personality, she single-handedly captures numerous criminals through brute force, earning recognition for her exceptional skills. One day, she apprehends an entire bank robbery gang and discovers that its members are addicted to a mysterious substance. Sensing the presence of a powerful underground syndicate—the Kito River Clan—operating behind the scenes, Natsumi defies her headquarters' orders and infiltrates their hideout alone. However, she is quickly discovered by Kurozawa, the clan's lieutenant, and captured by his combat machine enforcer, John. Overpowered and completely restrained, Natsumi is fitted with spiked iron balls attached to her limbs and abdomen, along with electromagnetic clamps that deliver electric shocks upon contact with metal. Enduring intense pain, she is connected to a mind-reading device and mounted onto a metal triangle horse. Whenever she gives false answers or refuses to respond to Kurozawa's interrogation, the Thunder Weight strapped to her back increases in mass, sending waves of excruciating pain through her groin. Can she maintain her integrity as a detective and preserve her dignity as a woman?