A hugely popular VRMMO with about 300 million players. Naoki, who started playing the game at his younger brother's insistence, was casually enjoying the virtual space with the tank class he chose without much thought. One day, due to the actions of a mysterious developer, nearly half of the players become trapped in the game. Naoki's brother was one of them... In the transformed game world, a game over means death in the real world. Naoki, a beginner who dived into the dangerous game world to save his brother, finds himself in a dire situation with only 1 HP when faced with berserk monsters. However, the tank class he chose harbored a powerful skill that no one knew about.