After being fired from her position as a saint, she somehow turned into a little girl and became the Demon King's pet.

【Comic adaptation begins on FLOS COMIC on April 6, 2022】

I was a saintess and the Crown Prince's fiancée. That's in the past tense because one day, a saintess was summoned from another world, and I was cast aside. To make matters worse, I was framed for a crime I didn't commit and, under the guise of an execution, thrown into a ravine. But when I awoke, my body had inexplicably become that of a five-year-old child! What's more, this seemed to be the Demon King's castle in the Demon Realm, and because human infants are rare, the Demon King took a liking to me and made me his pet. Even though I worry that I'll be killed if my true identity—as the one who erected the barrier between the Demon and Human Realms—is exposed... I just can't seem to escape the Demon King's castle, with all the delicious meals, sweets, naps, and cute clothes. Thus begins a mysterious pet life for the child I've become (the former saintess) and the Demon King who dotes on me!

◆ Also published on Kakuyomu.