The plot is set in the trade city of Ert'Aria. Leicester Maycraft is an item engineer in the adventurer guild "Oasis." One night, he and his companions are enjoying a party when they notice a meteor stream on the roof of a chapel. One of the meteors grazes them and lands on the chapel's spire. There, he discovers a hidden chamber and a sleeping girl. The girl awakens and exclaims, "You must be my father!" The contact with the unusual girl brings Leicester an unexpected adventure.