Sensei Gimberline is a presenting the bunkai of Heian (Pinan) Yondan.
Historcial background: When karate was introduced from Okinawa to mainland Japan, its curriculum was modified to be more suitable for teaching in large group settings. In the case of kata, explanation of the brutal self-defense applications behind the movements were mostly removed from the teaching. These applications have remained largely a secret to most karateka for nearly a century. To this day, most karateka have little or poor knowledge of the application of the kata they practice every week. In the last few decades, many dedicated karateka have begun to search deeper to understand these techniques and reintroduce them to the teaching curriculum.