Sleepy Princess in the Demon Castle manga volume 24 features story and art by Kagiji Kumanomata.

Another milestone for the Demon Castle is (unintentionally) celebrated with surf, sand, and sun. Quilladillo discovers the hidden costs of fame, while Vampire discovers the incredible power of normalcy. A quest for a free pillow goes awry when a brief trip to the home of the Divinities results in Princess Syalis and Poseidon coming face-to-face with Somnus—the god of sleep. Plus, river races, idol groups, Angel Teddies, part-time jobs, and the Demon Castle residents like you’ve never seen them before!