Hiroshi "Monsieur" Kamayatsu (かまやつひろし, Hiroshi "Monsieur" Kamayatsu, 12 January 1939 – 1 March 2017)[1] was a Japanese singer and guitarist born in Tokyo.

He composed the music for Download,[2][3][4] a direct-to-video anime release based on PC Engine games.

"Monsieur" was a founding member of bands The Spiders,[5] Vodka Collins,[6] and also a solo act.

In 2001[7] he had a reunion with some former members of The Spiders, as the band Sans Filtre.

Kamayatsu died from pancreatic cancer on 1 March 2017, aged 78.