Maou-jou de Oyasumi

The Demon Lord Tasogare's castle is a dark and frightening place, filled with monsters that would terrify anyone unfortunate enough to be imprisoned there. But the human princess Aurora Suya Rhys "Syalis" Kaymin is different. She isn't scared of her situation, she just wants to sleep. Since the demon lord kidnapped her from her kingdom, she hasn't had a single good night's rest.

To help her get some shut-eye, Syalis uses whatever she can find in the castle. She makes use of the fur of fluffy demonic teddy bears and the silky, blanket-like bodies of ghost shrouds to make items that can help her sleep. Nothing will stop the sleepy princess, not even death.