A massive stadium. At its center, you slowly enters. From the audience seats, cheers for the coming battle roar. Here, there are no restrictions at all. The weapons you uses are free. Swords, spears, guns, or even unknown weapons are fine. Techniques are free, magic is free. Summoning giant weapons or battle robots and attacking with overwhelming firepower is even permitted. And this stadium itself is also an extraordinary existence. The walls, floor, ceiling, audience seats—all of it is made from an ultra-durable special material, and no matter how powerful the attack it receives, it will never be destroyed. Explosions, slashes, magic, even the bombardment of giant weapons cannot damage this place. In the center of the battlefield, a single Sandbag-kun stands quietly. You can do anything to him. And the upper limit of his durability is—the extreme countless number. "Come on, you. Choose any weapon you like. Use any technique you like. Hit him as much as you like." The audience erupts all at once. —The greatest durability measurement in history begins now.