This is a manga where the captured princess is not the damsel in distress. She does what she likes and will do what ever it takes to achieve a good nights sleep. This usually causes trouble for the demons as they have to clean up the mess she has caused.
What about the hero party coming to her rescue? Does the princess even care? The answer is nope. She just wants to sleep.
Every chapter we are presented with a new revolutionary ingenious idea the princess came up to with enhance the quality of her sleep. This involves the theft of items around the castle to conjure up equipment for the sake of sleep, meanwhile sabotaging the demons plans and the heroes progress alike inadvertently. Often oblivious of the consequences of her actions (and she doesn't care either), all for the sake of sleep.
This manga can be easily described as a unique story with unique characters, very different from the usual cliche fantasy stories. It's also packed full of funny references. You will not regret reading this and you will definitely laugh a lot in the process.