"Btooom!" is a survival action manga series written and illustrated by Junya Inoue. The story centers on Ryouta Sakamoto, a 22-year-old unemployed man who is one of the top players in the online multiplayer video game "Btooom!" The game revolves around strategic combat using various types of bombs, requiring players to outwit and eliminate opponents in a battle royale setting. Ryouta's life takes a drastic turn when he suddenly wakes up on a remote island, equipped with a bag of bombs and a small GPS device embedded in his hand. He quickly realizes that he has been forced into a real-life version of the game, where survival depends on killing other participants.

The island is populated by other players, each with their own motivations and strategies. Ryouta struggles to reconcile his gaming skills with the moral implications of taking real lives. Early in the story, he encounters Himiko, a fellow player and a skilled sniper in the game. Initially distrustful, the two form an uneasy alliance as they navigate the dangers of the island. Himiko's traumatic past and Ryouta's determination to survive create a dynamic partnership that evolves throughout the series.

As the story progresses, the participants uncover the sinister motives behind the deadly game. The organization orchestrating the event, known as BIMCOM, selects players based on their personal histories and psychological profiles, using the island as a testing ground for human behavior under extreme stress. Ryouta and Himiko encounter a variety of adversaries, including Kiyoshi Taira, a former soldier with a ruthless approach to survival, and Masashi Oda, a manipulative and cunning player who thrives in the chaos.

The narrative explores themes of trust, morality, and the psychological toll of violence. Ryouta's growth as a character is marked by his struggle to maintain his humanity while adapting to the brutal reality of the island. The series also delves into the backstories of other participants, revealing the circumstances that led them to the game and adding depth to the overarching conflict.

The plot builds toward a climactic confrontation with the masterminds behind the island, as Ryouta and Himiko seek to expose the truth and escape the deadly game. The manga combines intense action sequences with psychological drama, creating a gripping and thought-provoking narrative. The series concludes with a resolution that ties together the fates of the main characters while leaving room for reflection on the consequences of their experiences.