First-year high school student Takuto has been chosen as a beta tester for the new sandbox-style video game Cube Arts, and he is thrilled. The moment he dons the game's VR headset, Takuto finds himself immersed in a vast world composed entirely of blocks, where he can mine, build, and hunt to his heart's content. However, when a logout error traps him and his friends inside the game, Takuto discovers that even sandboxes can be deadly!