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.
While low-ranking angels under Zeus's guidance attempt to earn their status by helping humans, Miki performs a peculiar purification rite for the amnesiac Yorishiro. Their efforts are interrupted during a lottery event when a mysterious agent sent by Hades kidnaps Yorishiro to drain his life force. Although the angels manage to rescue him from the monsters, the encounter reveals a growing conflict between Zeus and Hades.