Protected by a great wall, the Holy Kingdom of Roble enjoyed a period of peace that lasted for years. But with the sudden appearance of the demon king Yaldabaoth and his army of vicious demihumans, peace and tranquility are shaken. Remedios, the Grand Master of the Paladins, and the High Priestess Kelart are gathering their forces to fight back together. But they are no match for the all-powerful Yaldabaoth alone. When the Holy Kingdom is on the verge of collapse, Remedios sets out with her order and her follower Neia in search of help. They eventually find them in the Sorcerer Kingdom of Ainz Ooal Gown, a strange nation ruled by the undead who are actually loathed by the people of the Holy Kingdom. Can they win the fight against the Demon King together?