Jōnin

Jonin (上忍, Jōnin?, literally "High Ninja", Viz "Elite Ninja") are generally highly-experienced ninja with great individual skill who serve as military captains. They are often sent on A-rank missions, and experienced Jonin may even be sent on S-rank missions (which are considered to be the greatest difficulty). They may also carry out these missions alone. They are sometimes assigned as sensei for three-person teams of Genin. It is as of yet unknown what one has to undergo to become one. It is mentioned in the Naruto Anime Profiles databook that Jonin are appointed, however there was mention of a Jonin exam in the Kurama filler arc. It is known that most Jonin are generally able to use at least two types of elemental jutsu.