Masaaki Hiyama (日山 正明, born Aki Masa, September 2, 1959) is a Japanese jazz drummer that participated in some of Japan's more well known fusion bands. He is a former member of Casiopea.
In 1979 he joined a fusion group called “Guitarist Creek”. They participated in Cross-Wind (a large fusion concert also known as East-West). Masaaki met Casiopea at this time. They became good friends. He also met Hidehiko Matsumoto and his group. He played with jazz vocalist Henri Kanno, Mikio Masuda, jazz pianist, and other jazz groups.
In 1990, Tetsuo Sakurai Akira Jimbo left Casiopea to form Jimsaku. Yoshihiro Naruse and Hiyama joined Casiopea.
In August 1992, Masaaki resigned from Casiopea due to health issues because of his smoking habit under doctor's advice. Masaaki recorded a total of four albums with Casiopea.
After regaining his health, he returned to jazz. He joined a music school that was dedicated to teaching.
Today, Masaaki participates in both rock and jazz fields in his drum project along with band members. His nickname is “the godfather” as given to him by Yoshihiro Naruse.