Maoujou de Oyasumi

Synopsis

From Viz: She decides to while away the hours by sleeping, but getting a good night’s rest turns out to be a lot of work! She begins by fashioning a DIY pillow out of the fur of her Teddy Demon guards and an “air mattress” from the magical Shield of the Wind. The princess’s hapless demonic guards soon discover that their captive expects to be treated like, well, a princess. Things go from bad to worse, for her captors, when some of Princess Syalis’s schemes end in her untimely, if temporary, demise and she chooses the Forbidden Grimoire for her bedtime reading.

Synopsis & details from MangaUpdates