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.