Mizoguchi started playing piano in 1963 at the age of 3 and the cello in 1971. From 19781985 he attended the Tokyo National University of Fine Arts and Music where he majored in violoncello. While at school he started playing the cello with Japanese popsingers and working as a studio musician for radio TV films and albums. In 1982 at the age of 22 he had a serious traffic accident which led to his composing. In 1986 he released his first album Half inch dessert being listed as composer arranger and performer. From that time on he has released more than 20 albums including motion picture soundtracks has performed in many concerts on his own or with ensembles has been a producer for various musicians and so on. By the late 1980s he was generally recognized as one of the leading musicians in Japan.