Three aspiring angels—Hesperis, Euproshne, and Aurora—are sent to Earth for a three-month promotion exam to prove their virtue by helping humans. After befriending a struggling flower shop owner, they attempt to navigate human life while keeping their divine identities secret. However, as they face earthly temptations and the sudden appearance of a monstrous "Sex Beast," they realize their test is far more complicated than they imagined, all while drawing the dangerous attention of the underworld.