Complex sentence: Due to a series of mishaps, he became the next heir to the Hashiguchi company, much to his displeasure, but eventually decides to become much like a Mafia boss anyway, and this caused all his subordinates to copy his hairstyle.
Split into simpler sentences: Due to a series of mishaps, he became the next heir to the Hashiguchi company, much to his displeasure. But eventually becomes much like a Mafia boss, and caused all his subordinates to copy his hairstyle.