Hiroshi “Monsieur” Kamayatsu is arguably the Brian Wilson of Japan. Monsieur was born in 1939 in Tokyo. His father was Jazz musician, and because of that influence, he started playing music in his early childhood. His debut was when he was a highschool student. The hit songs he composed for his Group Sounds band The Spiders(formed in 1963) in the mid 1960s are gems, and still hold up as classics today in the Japanese market. The Spiders were a Japanese band in the Group Sounds era that were one of the top three bands of that genre, a cultural pop music scene unique to Japan. "Monsieur" has also been a member of Vodka Collins and also a very successful solo act. Vodka Collins is a Tokyo based Japanese-American rock band, formed in 1971 after the end of the Group Sounds era in Japan. A supergroup in the Japan domestic market, Vodka Collins' core band members are drummer Hiroshi Oguchi, singer-guitarist Alan Merrill, singer-guitarist Hiroshi "Monsieur" Kamayatsu and bassist Take Yokouchi. All of the Vodka Collins released works are original compositions by lead singer Alan Merrill. The band has made 5 albums, the most well known being the glam rock album "Tokyo - New York" released in 1973 on EMI records. Other album titles are "Chemical Reaction", "Pink Soup", "Boy's Life" and '"Boys In The Band".

In recent years, he had worked with various different musicians. Especially he tended to work with young cutting-edge musicians such as Yuming, The Alfee, and Cornelius from different genre, and he released many singles and albums with them.

Because of his popularity among different generations, he has been invited to numerous music festivals and concerts as a guest and played for audience with diverse generations. In August 2006, he collaborated with legendary Japanese rock stars on an album called A Tribute to Brian Jones. This album was issued to pay a tribute to the memory of Brian Jones. He has been going strong performing for 5 decades, and is as popular now as ever on the scene. He is a true legend in Japan.