History: The legendary tiger attacked the leaf village at the same time as the Nine tailed fox. It is unknown if these two teamed up to destroy the leaf. The fourth hokage taught Shirukas mother the Hakke no Fuuin Shiki - Eight Divination Signs Seal Style. When it attacked the village his mother sealed the Legendary Tiger inside of him. That is how Narutos mother died.
Advantage: Get to use the Tiger's chakara. (since Jiraiya is his and Naruto's Grandfather he was trained in using it's chakara). Has a tiger tail all the time.
Disantvantege: Sometimes when he gos into the jinchuuriki modes the tiger takes over
Demon/whetever is sealed in you INFO: Yukibub (Legendary Tiger)