Lucas Giulio was a mafia boss. His late mother was a witch. Before passing, she gave him a necklace which could summon the great ancient demon, but nobody knew. When Lucas was kidnapped by the rival gang due to his right-hand man’s betrayal, he summoned the demon unintentionally by drenching the necklace with his blood. Now, with a random demon appearing in front of Lucas, who was an atheist, what would happen?