横浜市立大学
Nishimaru was born in Yokohama. He studied Medicine at Yokohama Medical College (present-day Yokohama City University School of Medicine), and was appointed Professor of medical jurisprudence there in 1973. While working at Yokohama City University, he wrote some enlightening essays on forensic medicine, including "Afternoon in the Forensic Medicine Classroom" which was made into a TV program in Japan. After retiring from Yokohama City University and becoming Professor Emeritus, he became a ship's doctor.