Complex sentence: He shares a room with Tokiya from Class S, later Class A. He's an orphan whose mother died in a plane crash and that never met his father; he decided to became an idol because he heard his father was one.
Split into simpler sentences: He shares a room with Tokiya from Class S, later Class A. He's an orphan-his mother died in a plane crash he has never met his father. Otoya decided to became an idol because he heard his father was one.