Born in 1974 in Tokyo. Studied composition at Kunitachi College of Music from 1983. At the graduation concert, " Fantasia für Kammer orchester und Kalavier" was performed with him as a conductor. Also, when he graduated in 1987, he received " Arima Prize " from the university. In 1987, he was given a finalists award in the composition division of the 56th Japan Music Competition by "From an Illusion for String Quartet". In the same year, he entered the Masters course in composition of Tokyo Geijutsu University. While he was there, he received the 2nd prize in composition division of the 57th Japan Music Competition by "The landscape covered in shadow for Orchestra". In 1990 he received a masters degree from the university. In 1994, "Furin (Windy Woods) for Shakuhachi, Sangen, Uchimono " was performed at the 132nd Regular concert of Japan Music Group (Nihon Ongaku Shudan) under his direction. Also in the same year, "Improvisation for Piano" was premiered at the 3rd Young Prague International Music Festival in Prague, Czech Republic, and at an musical evening titled " Singing Chuya " which is a part of " Yamaguchi World Music Festival .... Japan " which was held in Yamaguchi Prefecture in Japan, "Image I, II" by the poem by Nakahara Chuya was premiered.
In 1995, "Standing Still (Tatazumite)" for Euphonium Solo was premiered at "Fukaishi Sotaro / Kurosawa Hitomi Euphonium Concert I". Since then, several pieces for wind and percussion instruments were written, and in 1996, the first personal show of Koyama was held in Tokyo with mainly wind/percussion pieces.
In 1997 Koyama received the first prize in piano duo division of the 4th International Composition Competition (in Japan). In May, "Hisho" for flute solo was performed at Winterthur in Switzerland.
On the academic side, he is a lecturer at Kunitachi College of Music from 1991. Also, he was a lecturer at Tokyo Geijutsu University from 1994 to 1996 (Music Theory). A member of The japn Federation of Composers inc.