Sakamoto Ryota is an unemployed 22 year old who lives with his mother and spends his days doing nothing but playing video games. In the real world, there may be nothing special about him, but online, he's one of the world's top players of the combat game called Btooom. One day, he awakes on what appears to be a tropical island, though he has no memory of how he got there or why. While exploring the island, Ryota runs into a mysterious being who attacks him by throwing a strange looking bomb at him. Ryota then realizes that both his life is in danger, and that he has somehow become trapped in a real-life version of his favorite game. Ryota and the other "players" must now survive through the nightmare to figure out the reason why they ended up in the game in the first place.