Wikipedia
Ashi-Hishigi
Ashi-Hishigi also called an Achilles lock or simply an ankle lock, is a technique described in both The Canon Of Judo by Kyuzo Mifune and Brazilian Jiu-Jitsu, Theory and Technique by Renzo Gracie and Royler Gracie as well as demonstrated in the video, The Essence Of Judo. It is classified as a joint lock (Kansetsu-waza), and is not a recognized technique of the Kodokan. However, It is a commonly used technique in both Brazilian Jiu-Jitsu tournaments and Mixed martial arts competition.