Sleepy Princess in the Demon Castle

🇯🇵魔王城でおやすみ · Maou-jou de Oyasumi

MangaShounenOngoing🇯🇵 First published in 2016ComedyFantasySlice of Life

Kagiji Kumanomata story, art

Sshhh! Princess Syalis is trying to get a good night's sleep. Some shut-eye. Forty winks. Catch some Z's. Long ago in olden times when people and demons lived together in—well, disharmony, really – a demon king kidnaps a human princess and imprisons her in his castle.

Synopsis via AniList