Murayama was born in Lahaina, Maui, Hawaii to Japanese immigrant parents from Kyushu. When he was about 12, his family moved to a sugarcane plantation camp at Pu'ukoli'i. (This was a company town of several hundred workers and their families that no longer exists.) Murayama's experiences there provided the material for his novels. After graduating from high school in Lahaina in 1941, he attended the University of Hawaiʻi. He served in the Territorial Guard after the bombing of Pearl Harbor, but was abruptly discharged with other Japanese Americans. He soon after volunteered with Military Intelligence. As a native speaker of Japanese, he was sent to Taiwan as a translator to help facilitate the surrender and repatriation of Japanese troops there.