The protagonist is a normal high school girl who was born in the Sacred Bird Cosmos. She and many other girls act as school representatives for a field trip to Holy Land the day after her seventeenth birthday. Like the other girls, she is asked by the Sacred Guardians to walk through a series of doorways. Her path ends at a mystical stone slab which shimmers in her presence. Moments afterwards, a spirit takes the form of her treasured childhood doll to inform her that she is the legendary étoile, or a celestial messenger for the cosmos. Her mission is to help nurture the Sacred Beast Cosmos's growth within a year (365 days).