hadaka jime

Hadaka-Jime is one of the twelve constriction techniques of Kodokan Judo in the Shime-waza list. It is also three (in variation) of Danzan Ryu's twenty-five arts in the Shime No Te list. In MMA it is known as rear naked choke.
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The rear naked choke (often abbreviated RNC) is a chokehold in martial arts applied from an opponent's back. Depending on the context, the term may refer to one of two variations of the technique. Either arm can be used to apply the choke in both cases.The term rear naked choke likely originated from the technique in Jiujitsu and Judo known as the "Hadaka Jime," or "Naked Strangle." The word "naked" in this context suggests that, unlike other strangulation techniques found in Jiujitsu/Judo, this hold does not require the use of a keikogi ("gi") or training uniform.
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Naked arm choke. A shime waza  technique.