Takanashi Yuma was working at the town festival when she finds a suspicious vendor and ends up winning a blank book. Apparently, the book grants any wish that is written on the pages.

Yuma magically gets transported into a different world where she has taken the role of the demon lord’s temporary replacement and the only way to return back home is to somehow find a way to resurrect the previous dark lord. Unsure if she is dreaming or not, she decides to go with it and starts gathering her demon legion to find a way to bring back the evil Deltoria.