Career
He was the assistant of Satoru Ozawa for four years before becoming Go Nagai"s first assistant in 1968. He debuted professionally in 1970 with Shichiju Shiki Sentoki for the magazine Weekly Shonen Jump of Shueisha, using the pen name Yukio Asai (浅井 ゆきお). With Silver Kamen in 1971, he started using the pen name of Mitsuru Hiruta.