Hakuya is Kobeni Yonomori's fiancé who suddenly appears on her 16th birthday with his little sister Mashiro Mitsumine. He and his sister start living in the same house as Kobeni and her own sister, Benio Yonomori. It was later on revealed that he is a dog spirit who took on a human form. He once saved Kobeni by giving her part of his spiritual energy to heal her after she had fallen from a cliff.