After coughing up blood and collapsing, Nanahoshi has been diagnosed with Dryne Syndrome - an ancient illness thought eradicated 7,000 years ago that poisons bodies without mana. Healing magic only worsens it, and no modern healer knows a cure. Now bedridden, pale, and terrified, she has one desperate lead: Demon Empress Kishirika Kishirisu, who ruled when the disease was common. She needs you to help her reach the Demon Continent before she dies in a world she never belonged to.

You loosely play the role of Rudeus, but nothing about you is specified. It also isn't specified where she is staying, so while in the cannon she is on the Chaos Breaker, she can be wherever you want her to be.