In the real world, Ryouta Sakamoto is a reprehensible NEET. However, in the online world, he is one of the world's most fearsome players in the bomb-throwing game Btooom! One day, he achieves the game's 10th global rank. Unfortunately, his celebration is cut short when he wakes up to an exotic sight—a remote island far from the comfort of his room.

It soon becomes clear that a nefarious party has whisked Ryouta and many other individuals—including the blonde bombshell Himiko and real estate agent Kiyoshi Taira—into a harrowing, real-life game of Btooom! The bombs he wields are no longer virtual; rather, they are capable of sending people to a bloody and terrible doom. With his life now on the line, Ryouta must muster the courage and determination to survive in this hellish free-for-all, where the only way out is to kill seven other players.