In 1984, Kazuhiko Aoki joined Square along with Square A Team director Hironobu Sakaguchi and B Team director Hiromichi Tanaka. He began as an assistant to Sakaguchi, collaborating with him on the scenarios for Cruise Chaser BLASSTY and King's Knight. In 1988 he formed his own design team, its first project being Hanjuku Hero. After the tremendous success of the Final Fantasy series, Aoki's team was absorbed back into the Sakaguchi group in order to work on development of Final Fantasy III.
Aoki most notably produced Chrono Trigger, while his other leading roles include directing the production of Hanjuku Hero 2, Chocobo's Mysterious Dungeon, it's sequel, Chocobo's Dungeon 2, and Final Fantasy Crystal Chronicles. More recently he served as planning director on Code Age Commanders and battle supervisor for the Nintendo DS port of Final Fantasy III.