Jiraiya is one of the legendary Sannin, along with Tsunade and Orochimaru, who was trained by the Third Hokage. He was a self-proclaimed super-pervert, and wrote a popular adult fiction book series, called Icha Icha--a favorite of Kakashi Hatake. He was also known as the Toad Sage, because of his signature toad summonings. Jiraiya had the kanji character for 'Oil' on his customized forehead protector.