Sleepy Princess in the Demon Castle (Japanese: 魔王城でおやすみ, Hepburn: Maōjō de Oyasumi, lit.

'Good Night in the Demon King's Castle') is a Japanese manga series written and illustrated by Kagiji Kumanomata.

[4] Despite the Demon King's best attempts, the princess turns her kidnapping into a vacation; having grown tired with the stress of a royal life, she is indifferent to the situation.

[87] On February 21, 2021, Funimation announced the series would receive an English dub, with the first episode premiering the next day.

[106] Anime News Network's staff included Sleepy Princess in the Demon Castle on their top 5 best anime list of 2020: Rebecca Silverman placed it at number four, praising the way the source manga gets cherry-picked and comes together as a whole, concluding that: "It's not only funny, but also one of the best adaptations I've seen, and I can't wait to start rewatching it as soon as it ends.

"[107] Caitlin Moore placed it at number five, praising Mitsue Yamazaki and Yoshiko Nakamura for adapting "already funny source material, tweaking the jokes, and incorporating split-second comic timing to make it outright hilarious.