Normally, fish become rigid about 4 hours after death, and after this rigidity, they progress to aging and putrefaction. Traditionally, fishermen have been squeezing nerves using piano wire or stainless steel wire. However, in order to pierce these wires along the spinal cord, it was difficult to slip through due to the slimy fish, and skillful skills were required. Also, hard materials such as piano wire were very difficult to pass through the curved spinal cord of fish. Therefore, by applying a special uneven processing (PAT.P) to the surface of an elastic linear wire, it is possible for even an inexperienced amateur to narrow down the nerve relatively easily. With the advent of this new tool, it has become relatively easy to tighten small horse mackerels to huge bluefin tuna.