The Roble Holy Kingdom, led by Holy Queen Calca, had enjoyed a peaceful era, protected by its vast walls. However, this peace was quickly shattered by the sudden invasion of the demon emperor Jaldabaoth and his demi-human allied forces.The kingdom, with its forces led by Holy Knight Commander Remedios and High Priest Kelart, gathered its strength to fight back. But the overwhelming power difference between them and Jaldabaoth left them powerless, and the nation faced the threat of collapse.

In search of a power capable of opposing Jaldabaoth, Remedios, accompanied by her Holy Knights and her follower Neia, set out to seek help from another country. The name of that country was the Sorcerer Kingdom of Ainz Ooal Gown—a grotesque nation ruled by the undead, detested by the people of the Holy Kingdom.