Eunseong works hard at various part-time jobs, trying to become independent from his abusive, alcoholic father. While struggling with his studies due to working and being tormented even by those he considered friends, a mysterious man appears. Yoo Siwoon, a man with a mysterious aura and a wolf tattoo, volunteers to be Eunseong’s guardian and…

The Grand Slayer of Demons—the great hero who taught me swordsmanship. I alone know the truth—that he has fallen and become the Demon King. Reborn into the family of my enemy, this second life… I will have my revenge. With magic.