Long ago, a fierce war unfolded between yōkai and humans. The leader of the yōkai, known as the 'Shukai', led the Hundred Demons Night Parade as they advanced northward across the islands. Their assaults were ferocious, driving humans into a series of desperate retreats. However, a samurai from the Mutsu region rallied the people, inspiring both warriors and commoners, as well as temples and shrines, to unite and fight back. In a collective effort, they managed to defeat the supreme chief and seal it deep underground. From that battlefield, a humble shrine took root. Yet, for generations, there was no sign of the guardian who was supposed to watch over the shrine. To once again seal the lurking supreme chief, a young heir must rise to the challenge—