According to legend, after the Earth was destroyed, the great clockmaker Y created a replacement out of cogs and gears. Naoto Miura is a young child who dreams of becoming a renowned clockmaker. Despite his extraordinary ability—sensitive hearing that can instantly grasp clockwork mechanics from noise alone—he has made little progress. But all of that changes when a coffin falls from the sky into his flat, exposing RyuZU, a female automaton created by Y himself. The entrance of RyuZU brings into Naoto's life Marie Bell Breguet, the talented heir of a prestigious dynasty of clockmakers, and her cyborg guardian Vainney Halter. When she and Naoto become entangled in an action-packed struggle for their lives, they uncover an unsettling truth: humanity's clockwork planet.