Upon Miura Naotsugu's request to find his elder brother, Jinya visits the Miuras' family home to investigate his disappearance. But as soon as Jinya and Naotsugu step into the missing brother's room, they are pulled into a strange, other world. There, they discover a little girl playing with a ball and the elder brother by her side... Was the brother spirited away by a demon, after all? A surprising truth awaits them as they unravel the mystery of his departure...