During the quest of Kazuma and his company, they find the "Black Slab" which has the ability to make outfits. Then they discover that the slab has a curse that can make one's desires the exact opposite.
Darkness turns into a ruthless and cool-headed queen, Megumin into a founder of loli-alliance, and Aqua turns into primp and proper goddess. Kazuma must use the Black Slab to break their curse by making outfits to fulfill their desires.