Eiji and Kouki are angels whose mission is to guide souls to either heaven or hell. Eiji, a black angel, guides corrupted souls to hell, while Kouki, a white angel, guides pure souls to heaven. Both have to work together as partners to accomplish their task. However, God cannot forgive black angels for their accumulated sins, and only gives white angels the power to reincarnate. Though Eiji develops strong feelings for Kouki, can he escape the cruel fate that God has given him?
White Angel Kouki and Black Angel Eiji must deliver departed souls into the afterlife. The angels age as they consume the souls in order to ferry the souls either to heaven or to hell. The unexpected happens as Eiji begins to age rapidly, leaving Kouki to wonder about the short time they have left together.