In a sprawling, futuristic city divided by class disparities, Dr. Laughton creates an advanced humanoid robot named Tima under the directive of Duke Red. Duke Red is a powerful industrialist who plans to use Tima as a tool to take control of Metropolis. Detective Shunsaku Ban and his nephew, Kenichi, arrive in the city to apprehend Dr. Laughton for his illegal activities. During their investigation, an accident results in Tima losing her memory, and Kenichi unknowingly takes on the responsibility of protecting her as they navigate the chaotic urban landscape.

Meanwhile, Duke Red's adopted son, Rock, becomes increasingly hostile towards Tima, seeing her as a threat to his father's position and intentions. The city's intricate network of underground zones, towering skyscrapers, and bustling districts serves as the backdrop for a series of escalating confrontations. As the power struggle intensifies, Kenichi discovers more about Tima's true nature and her connection to the ambitions of those controlling the city. The narrative explores themes of identity, technology, and social order, drawing towards an impactful conclusion as secrets unravel and destinies collide.