Everyone between the age of 15 and 25 worldwide is required to participate in the death game of twenty rounds. The main character starts his 100th challenge thanks to his ability to regress. Having experienced the game 99 times beforehand, he is able to become overwhelmingly more powerful than anyone else. Once he realizes that the condition of the last round is to have at least five people, he starts to take in party members in order to avoid repeating his past mistakes.