Grandpa sends his regrets.

In his youth, a young man named Caiben led a deranged cult in the city, surrendering his soul to a foul demon. Years later, he regretted his actions, fled the cult, and returned to his family in the countryside. Many years passed, and Caiben had a family of his own. His former life long behind him—or so he believed—he settled in to live out his days quietly as a grandfather, his lifespan protracted by the foul magic in which he once consorted.

The demon, however, refused to free Caiben, now Grandpa, from the bargain of his promised servitude and caught up with Grandpa at the farmhouse, where it tormented him day and night until he went insane. Years later, the demon and Grandpa remain, the latter a worn-out derelict of a man, and the demon now desires a fresh host.