Four hundred and fifty-six people, most of whom are experiencing serious financial problems, accept an invitation to participate in a mysterious tournament for children's games. It quickly turns out that this is a survival tournament. After a player withdraws from the competition, the prize amount increases by 100 million won, meaning the winner of the tournament will receive 45.6 billion won (at the time of the series' creation, this is equivalent to 38.5 million US dollars).