At the request of her childhood friend Ryota’s parents, Hikaru agrees to care for his elderly grandfather Kozo. Having lost his will to live after his wife’s death, Kozo finally smiles again in the presence of the angelic Hikaru. She worries about his health and gives him warm, intimate care as if he were family. Ryota, who secretly loves Hikaru, grows jealous of their bond and plots to destroy it—but his scheme only draws the pair deeper into an obscene and forbidden world.