Himitsu: Kuro no Chikai

Rin, a young angel (presumed female, though angels exist beyond human concepts of gender), finds her heart drawn to a human girl named Miku—a connection that defies the natural order between celestial and mortal realms. When their bond proves impossible within the rigid laws of both heaven and earth, Rin faces an impossible choice that will reshape her very existence. Through a mysterious transformation that bridges the divide between divine and human, Rin gains the chance to walk among mortals, though the path ahead remains shrouded in uncertainty. Their story explores the lengths one will go to for love, and the profound consequences that ripple outward when the boundaries between worlds begin to blur.