In the year 1977 in Yonaki Village, Kazunari Honda and Natsuko Honda—his cousin and girlfriend—live a peaceful life despite most of the other villagers not approving of their relationship. But soon, they will have more to worry about than the opinions of the townsfolk, as a mysterious black envelope appears and informs the villagers that they will be participating in the "King's Game." The rules state that the commands must be followed by the end of the day, and that no one is allowed to quit. With most viewing the appearance of the envelope as a joke, they soon realize that those who don't obey the orders will die.

As more villagers meet their demise, Kazunari and his friends realize they must play the terrible King's Game, all the while suspecting that someone in the village may be the King.