Koto accidentally traps the Sun Goddess Amaterasu in a different world, leaving neither of them a way back. While exploring this unfamiliar realm, Koto meets priestesses who are battling the darkness that afflicts their land. She learns that Black Towers erected across the region are keeping Amaterasu imprisoned, with each tower guarded by dangerous creatures. Koto's mission involves allying with these priestesses to defeat the monsters and free Amaterasu, thereby restoring harmony to the world.