Complex sentence: Shigeru Kawai was president of the Kawai company from 1955 to 1989, chairman from 1990 until 2002, and a company consultant until his death in 2006 at 84.
Split into simpler sentences: Shigeru Kawai was president of the Kawai company from 1955 to 1989 and chairman from 1990 until his retirement in 2002. He remained active as a company consultant until his death in 2006 at 84.