Forty-two-year-old salaryman Takahiko Ago awakens to find his world subtly but horrifyingly transformed: it is still modern Japan, but now the most popular entertainment is D-Sports, a nationally televised competition in which killing is not only permitted but celebrated. Losers are executed on the spot, and rule violations carry the same penalty. Ago, a mild-mannered office worker at a sporting goods company, is forced to become a contestant. The first event, the D500m run, is a lethal footrace where participants can use weapons in the final stretch, and the crowd cheers for bloodshed. Ago survives through a combination of physical grit and desperate ingenuity, but he is marked by the system. The second event is a climbing challenge that pushes him further into the arena of death. The third event, D Beach Volleyball, uses explosive balls—one mistake means instant detonation. The fourth event, D Clay Shooting, replaces the clay targets with humans holding the discs, and Ago must shoot real bullets at them without error. As he endures these sadistic trials, he forms uneasy alliances and makes enemies, particularly with the ruthless competitor Kijima. His growing notoriety brings him into contact with the prime minister, Kujira, who holds the secrets behind D-Sports and the true nature of this altered world. The story follows Ago’s struggle to survive each brutally inventive event, his refusal to be corrupted by the sport’s cruelty, and his gradual uncovering of the conspiracy that turned murder into a spectator sport. The narrative arcs through escalating physical and moral challenges, testing whether one ordinary man can hold onto his humanity in a society that has made slaughter a game.