Complex sentence: Besides being a composer he has been a producer and music supervisor for many years and now has his own publishing company "Hattori Music Publishing", he also is of Pianist, judge and a chairman for the Tokyo music festivals.
Split into simpler sentences: Besides being a composer, he has been a producer and music supervisor for many years, and now has his own publishing company, "Hattori Music Publishing". He is also pianist, judge and a chairman for the Tokyo music festivals.