Complex sentence: Shiina is the same age as Ayumi Hamasaki and MISIA who entered the music industry in the same year, and they are all from the same city, Fukuoka-shi.
Split into simpler sentences: Shiina is the same age as Ayumi Hamasaki and MISIA. They all entered the music industry in the same year, and they are all from the same city, Fukuoka-shi.