High school first-year Takuto has been selected as a beta tester for the new sandbox-style video game Cube Arts, and he couldn't be happier. As soon as he puts on the game's VR headset, Takuto finds himself immersed in a sprawling world made entirely of blocks, where he can mine, build, and hunt to his heart's content. But when a logout error traps him and his friends inside the game, Takuto discovers that even sandboxes can be deadly!