Complex sentence: Itoh was the original saxophonist of T-Square from 1978 until 1990 when he left the band due to several problems and was replaced by Masato Honda who is now pursuing his solo career and later replaced by Takahiro Miyazaki who is also pursue his solo career.
Split into simpler sentences: Itoh was the original saxophonist of T-Square from 1978 until 1990 when he left the band due to several problems. He was replaced by Masato Honda who is now pursuing his solo career.