Kidnapped by the Demon King and imprisoned in his castle, Princess Syalis is...bored.

The sun shines on the Demon Castle...but it's supposed to be perpetual night in the Demon World Then Zeus--Poseidon and Hades' little brother--joins the Demon Castle staff. Everyone is in awe of him except the princess, who quickly finds ways to use the most powerful of the mythological gods to help her achieve her ongoing and current personal goals of sleeping better and opening a cat cafe. Then, in a stunning reversal of fortune, an important castle inhabitant is taken hostage Will Syalis help the rescue team's efforts or hinder them? Plus, a very special Sleepy Princess/Doraemon crossover episode