Ryouta Sakamoto is unemployed and resides with his mother, his sole significant accomplishment being his status as Japan's top player of the popular online video game Btooom!. However, his tranquil existence is poised to shift when he awakens stranded on a remote island, a small green crystal embedded in his left hand and no recollection of how he arrived. To his astonishment, someone has chosen to recreate the game he cherishes in reality, with the stakes being life or death. Equipped with a bag of unique bombs called "BIM," the participants are ordered to kill seven of their peers and seize their green crystals to secure their return home. Initially rejecting all violence, Ryouta is compelled to fight upon realizing that many other players are far less amiable than they appear. Joining forces with Himiko, another Btooom! player, they strive to escape the island together, drawing nearer to the truth behind this deadly contest.