Able to grasp objects of any shape and size, universal grippers using variable stiffness phenomenon such as granular jamming have been developed for disaster robotics application. However, as their contact interface is mainly composed of unrigid and burnable silicone rubber, conventional soft grippers are not applicable to objects with sharp sections such as broken valves and glass fragments, especially on fire. In this research, the authors proposed a new method of variable stiffness mechanism using a string of beads that can be composed of cut-resistant and incombustible metals, arrange the mechanism to form a torus gripper, and conducted experiments to show its effectiveness.