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Ana-tsurushi (穴吊るし, lit. "hole hanging"), also known simply as tsurushi (吊るし, lit. "hanging"), was a Japanese torture technique used in the 17th century to coerce Christians ("Kirishitan") to recant their faith. The victim was hung head-down by the feet. Both Japanese and Western Christians are known to have been submitted to the torture. One of the victim's hands would be held tight with a rope, but the other would be left free so that he could signal his willingness to recant.
The technique was said to be unbearable for those submitted to it, though some particularly resilient martyrs like Lorenzo Ruiz never broke under torture. The body was often lowered into a hole, itself often filled with excrement at the bottom. Typically, a cut would be made in the forehead in order to let blood pressure decrease in the area around the head.
Christians were let go after apostatizing, and in this way the Shogunate practically purged it from Japan.