In a magical world where demons threaten humankind, a young woman with a magic sword rises up to be their champion! Theres just one problem: the reigning demon lord is a baby, and she cant exactly slay a baby. Even if this domineering demon baby has crass tastes and evil DNA, she believes he can be turned to the side of good with the right influence. Unfortunately, shes forced to test the theory when a contract binds her to the baby demon lord as his surrogate parent until he performs enough good deeds to prove his worth. What kind of role is that for a mighty hero?