Perhaps this book will seem crazy. But if you are open to new ideas, the book will be useful.

Smugglers brought crime fighting techniques to Okinawa. These techniques are very dangerous and are aimed at the Adam's apple and damage to the cervical vertebrae mainly. Most of these techniques are lost, but some are still in use in China and Siberia criminal environment.

Demo video: https://youtu.be/OyaIDN2FzQE