Btooom! follows Ryouta Sakamoto, an unemployed young man who still lives with his mother and has only one real claim to fame: he is Japan's top player of the popular online game Btooom! That skill becomes a curse when he wakes up stranded on a remote island, a green crystal embedded in his left hand, with no memory of how he arrived there. Soon he realizes that the game he mastered has been recreated in reality, and that the rules now carry a deadly cost.
Each participant receives a bag of explosive devices called "BIM," and the only way home is to kill seven other players and take their green crystals. Ryouta initially refuses to embrace violence, but survival quickly forces him to adapt as the island's other players prove far more dangerous than he expected. He eventually teams up with Himiko, another Btooom! player, and the two try to escape the island together while piecing together the truth behind the contest. As they move deeper into the mystery, Btooom! becomes a tense fight for survival built on uneasy alliances, shifting trust, and the brutal logic of a game that no longer has anything virtual about it.
