Complex sentence: In 2000 he became semi-retired, staying Chairman of the Board while Idei became Executive Chairman, and on his 73rd birthday in 2003 Ohga retired from the board and became Honorary Chairman.
Split into simpler sentences: In 2000 he became semi-retired, staying Chairman of the Board while Idei became Executive Chairman. On his 73rd birthday in 2003 Ohga retired from the board and became Honorary Chairman.