The story centers around Ryūta Sakamoto, a NEET (Not in Education, Employment, or Training) young man and a top-ranked player in the online combat game Btoom! One day, he wakes up on a tropical island without remembering how he got there. He sees a figure in the distance and asks for help. However, the figure responds by throwing something at Ryūta — a "BIM" bomb. In that moment, Ryūta comes to realize two things: one, his own life is in danger, and two, he is now in the world of Btoom!