He graduated from Aoyama Gakuin University. Watari belonged to the karate club at university. He made his screen debut in 1964, in Isamu Kosugi's Abare Kishidō, and received one of the Elan d'or Awards. At Nikkatsu, Watari appeared in such films as Tokyo Drifter and the Outlaw series.
Watari was mentored at Nikkatsu by Yujiro Ishihara. When Nikkatsu shifted to focusing on Roman Porno films in the early seventies, Watari was one of many actors who left the studio.
Watari was due to play the main role in Kinji Fukasaku’s film Battles Without Honor and Humanity, but because of illness he was not able to appear. In 1974, he was forced to step down from the lead role of Katsu Kaishū in the Taiga drama Katsu Kaishū on NHK, again because of illness, after appearing in only nine episodes. In 1976, Watari won best actor of Blue Ribbon Award for his role in Kinji Fukasaku`s film Yakuza Graveyard.
