Seijo wo Kubi ni Nattara, Nazeka Youjoka shite Maou no Pet ni Narimashita.

I, Presea, had put up the defensive barrier between the human world and the demon world as the saintess. But in the end, I was executed for a crime I did not commit. When I woke up, I found myself in the Demon Lord's castle. Somehow, I had reverted to the form of a young girl, but with the power of a full-grown saint, and I am now living in the demon world as the Demon Lord's pet! Surrounded by cute dresses and tasty sweets, my days are full of happiness, but there are also many details that may reveal my true identity! Moreover, it seems that the Demon Lord has some secrets of his own.......? The heartwarming, sometimes escapist, and sometimes boisterous days between a young girl and the Demon Lord are about to begin! (Source: Kadokawa Books, translated)