Born in Minami-Uonuma, Niigata Prefecture, Japan in 1947. In his final year of high school, he moved to Tokyo, where he became involved in nationwide student protests in 1968. The following year, he was arrested during demonstrations at Tokyo University. On the advice of film critic Ryuho Saito, he began devoting himself to film. In 1983, he met members of the Sanya Winter Struggle Support Volunteers. In November 1984, he moved to the Tokyo neighborhood of Sanya to capture the struggles going on there. Filming for Yama – Attack to Attack began shortly after that, on 5 December; on 22 December, Sato was fatally stabbed by a member of the Nishido gang. He was 37 years old.