びわ湖毎日マラソン
Outside of the Olympics, Hiroshima experienced much success on the Japanese marathon circuit. He made his first impact at the Japanese national championships: becoming the national champion for the first time in Tokyo in 1953 and for a second time in Fukuoka in 1955. Between 1953 and 1959 he often registered within the world's top twenty fastest marathon runners of the year. He was a three-time winner of the Lake Biwa Marathon, with victories in 1955, 1957 and 1959.