A young man named Hayase Kazuya finds himself transported to Tokyo after the death of his parents. He lives with his adopted sister, has a substantial bank account, and expects his new life to be like a typical galgame. However, his sister reveals herself to be Tamamo no Mae, a nine-tailed fox yokai, who claims responsibility for the deaths of his ancestors and sets her sights on him. Instead of succumbing to fear, Kazuya attempts to cooperate with the powerful yokai.