The ability to fly is awakened in 1 in 10,000 males.

In a world where this is the norm, Iris, who dreamed of flying, awakens her ability to fly at the age of 15, even though she is a girl. According to past records, the only female who could fly was St. Angelina, who is said to have existed 700 years ago. Iris's life changes drastically when her ability blossoms. Iris is the only female knight to join the Royal Air Knights, a group that protects the kingdom from the giant bird Dalion, and is admired by the people of the kingdom.