Long after the events in Tales of Phantasia, a shooting star falls onto the planet. A stranger notices that the star holds two children, which happen to be siblings: a boy named Dio, and a girl named Mel.

Thirteen years later (Aselian Calendar 4408), Dio finds a creature on the mountainside, and names it Kruelle, keeping it as a pet. They lead normal lives, until a strange winged woman arrives and changes their destiny forever...