A young and unmotivated gamer named Arisu and his two friends, Karube and Chota, find themselves hiding in a public bathroom in Tokyo to escape the police. When they emerge, the entire city is mysteriously deserted. While exploring the empty streets, they are forced to participate in a deadly game. They learn they are in a parallel version of Tokyo, known as the Borderland, where they must compete in dangerous games to survive.
The games are divided into categories represented by playing card suits: Spades tests physical prowess, Clubs emphasizes teamwork, Diamonds challenges the intellect, and Hearts is designed to break players psychologically. The number on the card indicates the game’s difficulty. Winning a game grants a “visa,” which is extended by the number of days on the card. If a player’s visa expires, they are executed by a laser beam from the sky.
As Arisu and his friends struggle to survive, they meet other players, including Usagi, a skilled and solitary mountaineer. They face brutal games, including a game of tag in a locked apartment building and a lethal game of hide-and-seek. The psychological torment of the Hearts games proves especially devastating, leading to tragic betrayals and the deaths of Karube and Chota, leaving Arisu shattered.
Arisu and Usagi form a partnership, seeking answers about the Borderland. They learn about the “Beach,” a fortress-like hotel where a large group of players collect cards. The leader, Hatter, believes gathering all cards will allow them to return to their world. Arisu and Usagi infiltrate the Beach, encountering its enforcers, including the ruthless militant Aguni and a mysterious and strategic player named Kuina.
The season culminates in a deadly, complex game at the Beach itself—a Hearts game called “Witch Hunt.” Paranoia and chaos erupt as players accuse each other of being a “witch.” Hatter descends into madness, and Aguni goes on a killing spree. Arisu solves the game’s logic, but at a tremendous cost, with many players dead. He discovers the game’s mastermind was manipulating events from within.
After the final game, the remaining ten players have collected the entire deck of cards. The sky then shatters like a screen, revealing that they are being watched by unknown, god-like entities. All face cards—the Jack, Queen, and King of each suit—appear floating over Tokyo, signaling that the next stage of the deadly competition, featuring even more difficult games, is about to begin.