The death game "BTOOOM!" charges headlong into the final phase!! Ryouta survives a fierce battle against his sworn ally, Kiyoshi Taira, but the scars left on his heart run deep. Meanwhile, Kousuke Kira, hungry for a rematch with Ryouta, wanders the island looking to get back into the game. But when he's cornered by a mysterious group with unfamiliar BIMs and a merciless team strategy, the devious junior high schooler will have to think fast if he wants to live long enough to settle the score with world ranker SAKAMOTO...!!