The people on the technically advanced planet Mota make experiments to create biomechanical creatures. But one day, a creature was created that appeared to be dangerous to the humans themselves. No signal came to the capital city from the experimental labs... You, a nameless young man living in Paleo, Mota's capital, are commanded to go to the labs and check the issue. Your friend Nei, a semi-human girl, goes with you, and other brave adventurers join you on what starts with a simple mission but develops into saving the entire world.
This game is also known as Phantasy Star II: Kaerazaru Toki no Owari ni in Japan.