To save the world from that which threatens it, Lystia—nicknamed Lys—and her partner spirit Ruka are on a grand journey to search for spirits across the lands.

During their journey, they happen across a partly deserted town called Litos, where they discover that something odd is afoot. They hear that the ruins just outside of town have turned into a dungeon. Larger on the inside than it is on the outside, it also changes shape every time someone enters it.

The culprit behind it all must be a spirit!

And so, Lys and Ruka embark on their dungeoneering exploration in search of whatever spirit now rests in the dungeon…