Arisu, Karube, and Segawa, three high school delinquents, are bored with their lives. During a fireworks celebration, Arisu wishes for a more exciting world—and his wish is granted. The trio is transported to a seemingly post-apocalyptic parallel world. After entering an empty festival, a mysterious woman informs them that they have already begun a game. Upon clearing it, she reveals that in Borderlands, survival depends on playing and winning games.