Natsuki Amakusa is a twenty-year-old genius detective assigned to the Tokyo Metropolitan Police Department, known for his extraordinary deductive skills and sharp intellect. His methodical approach to crime-solving is turned upside down when he encounters Yuya Shiki, a quiet seventeen-year-old high school student who possesses an unusual innate ability: he can see a mark on murderers, identifying them instinctively. After Yuya helps resolve a complex case that baffled even Natsuki, the detective recruits him as an unofficial partner. Together, the two form an unlikely buddy-cop duo—Natsuki relying on logic and evidence, Yuya guided by his inexplicable gift. Across the series, they confront a stream of difficult and often dangerous cases, from serial murders to hidden conspiracies, while gradually unraveling the truth behind Yuya’s mysterious power and the consequences it carries. Their partnership deepens as they face threats that challenge both Natsuki’s faith in reason and Yuya’s struggle to understand his own nature, all set against the bustling, crime-ridden backdrop of modern Tokyo.