The sennin were legendary sage-like figures in old Japan.
Jiraiya, Tsunade and Orochimaru are three of the most famous sennin.
by glimmung May 27, 2006
Ero-Sennin is Japanese for perverted hermit. Also see Jiraiya
You're such an Ero-Sennin, Jiraiya.
by Freud December 8, 2004