Transparent Escape Technique

This technique has never actually been seen in the series, but allows the user to spy on others without being noticed. It was invented by Jiraiya in his youth to allow him to spy on girls bathing without the risk of being caught.

Trivia

 * Interestingly, the Third Hokage was also interested in this technique, prompting Jiraiya to speculate that his sensei was as perverted as he was.