This group, formed in 1962, was popular throughout the 1960s; they spawned several hit songs as well as thirteen situation comedy films featuring their music.

Due to his fame playing the mythical character Songoku, Sakai created a dance called "the Monkey" which became a craze in Japan.

Prior to taking the role in Monkey, Sakai learnt the art of staff known as Bōjutsu for 2 years.

Sakai is known in Japan as a car enthusiast and regularly took part in the annual Mille Miglia race in Italy with his wife as a co-driver.

He won a similar Japanese road race on October 18, 2000 driving a 1947 Cisitalia 202 MM with Inoue Takayuki (the guitarist from Sans Filtre) as co-driver.