While playing in the snow one day at her shrine, the land god Nanami Momozono witnesses her familiar—the fox youkai Tomoe—collapse, with dark markings appearing on his body. Tomoe's former master, Lord Mikage, appears after his long absence and places Tomoe into a magical pocket mirror in order to stave off his ailment. Mikage explains that long ago, before he and Tomoe had met, the fox youkai was in love with a huma...