Storing elastic energy in a soft body and releasing it instantly enables ultrafast movement beyond muscle capability, which small animals (mainly arthropods) realize. We applied this mechanism to a soft robot to achieve locomotion on top of a tubular surface such as a branch (i.e., upside-down brachiation). To achieve arboreal locomotion, the robot must have strong grippers to support its body and minimize the duration of time when one gripper is off the branch. By using a simulation model and prototype, we demonstrated that storing and releasing elastic energy in a soft body satisfies these requirements, allowing us to fabricate a lightweight robot. The prototype completed one step of the locomotion process in 0.22 secs, making it 2.3 times faster than the original speed of the mounted motor. In addition, we confirmed that the robot climbs 0- to 90-degree branches.