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Manga / Sleepy Princess in the Demon Castle

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Tragedy has struck the human kingdom of Goodereste, for their beloved princess has been captured by the vile Demon King who has declared that he will only return her if the humans surrender the world to him.

What evils will Princess Aurora Sya Lis Goodereste have to face while she waits for a brave and strong hero to rescue her?—is what the humans wonder, but the princess is more concerned with finding a nice place to get a good night's rest, and woe to anyone who gets in her way.

Sleepy Princess in the Demon Castle (Maou-jou de Oyasumi, also known as Sweet Dreams in the Demon Castle and Sleeping Princess), is a genre mix of Slice of Life, comedy and high fantasy by Kumanomata Kagiji. VIZ Media has licensed the manga for English release. An anime is scheduled to premier in 2020.

Has nothing to do with "Sleeping Princess in Devil's Castle", the second Non-Serial Movie in the Dragon Ball franchise.



  • The Ace: Raikou's adept at a wide variety of things: fencing, athletics, cooking, archaeology, mountain climbing...
  • Adaptation Dye-Job: In color art for the manga, the Princess has white hair, sometimes with a faint purple tint. The anime gives her light purple hair.
  • Anthropomorphic Personification: The spirit of the grimoire Al Azif manifests as a young boy in Ancient Egyptian-style clothing.
  • April Fools' Plot: In chapter 94, the Princess takes the Demon King's April Fool's prank seriously, thinking the castle's about to be destroyed, and the demons have to convince her it's not actually true.
  • Attack of the 50-Foot Whatever:
    • The Princess in chapter 59, although it's only temporary.
    • In chapter 61, the Princess's Eggplant Seal evolves into a larger form. A much larger form.
    • Former Demon King Midnight grows as he accumulates magical energy, and is currently giant-sized.
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  • Background Halo: Inverted with the cover of volume 3, which has a blood-red crescent moon positioned in just the right spot to make it look like the princess has horns.
  • Be Careful What You Wish For:
    • According to the volume 2 extras, the baku wanted quantity over quality for nightmares... then the Princess showed up, and he ended up getting so many nightmares he got indigestion.
    • The demons spend an entire week trying to get the Princess to act more like a hostage, but every plan fails. The one plan that does seem to work though ends up backfiring as everyone becomes hurt and depressed at having the Princess treat them like vile monsters (even though she was faking it).
  • Bifauxnen: Raikou, unknown to the demons.
  • Box-and-Stick Trap: The Demon King uses one to recapture the Princess after an escape attempt (because she wanted to go shopping in the human realm). There was a futon inside the trap, and it closed when she fluffed the pillow.
  • Card-Carrying Villain: The demons are officially evil, more or less because it's part of their job spec. And while they can be brutal dealing with human heroes that try to rescue the princess, they otherwise seem to limit themselves to harmless villainy.
  • Cardboard Prison: The demons might as well leave the Princess's cell door open for all the good it does (if nothing else, the Teddy Demons will just give her another copy of the key in exchange for another round of brushing). Later on, they just stop caring as long as she isn't wreaking havoc. It's even shown that the Princess, in spite of her penchant for escaping custody, has no intention of leaving Demon Castle even when she has all the capacity to do so, and then some.
  • Childhood Friend Romance: In a manner of speaking. The princess and the hero are childhood friends and are engaged... but the princess doesn't even remember the hero's face or name (and doesn't really care to remember) because he apparently made so little of an impression on her when they were young (her image of his face is henohenomoheji, representing anonymity).
  • Christmas Episode: Syalis writes a letter to Santa asking for a high-tech sleep pod, and knits a stocking large enough to hold it. However, the demons unanimously agree that she's the naughtiest person they know, and she wakes up in the morning to find the stocking full of coal and potatoes. The following chapter, she tries to win that pod by rigging the bingo tournament at the Castle's Christmas party (which she also uses to get rid of all the coal and potatoes), but she falls asleep during the Demon Cleric's interminable speech early in the evening. The pod was won by Ice Golem, who turned it into a bobsled. The following year, the Christmas arc centers around the demons taking the Princess back home so she can retrieve her winter wardrobe. The year after that, the demons decide to play Santa for her after she gets another stocking of coal and potatoes.
  • Coincidental Accidental Disguise: The Princess's Tire Demon armour gets covered in frost while exploring the Ice Region in search of some way to cool her cell. The inhabitants mistake her for their area boss Ice Golem, which she exploits to get an igloo constructed in her cell. She also takes advantage of the resemblance on subsequent visits.
  • Comedic Sociopathy: Courtesy of the Princess. She has free run of the Demon King's castle, and regularly terrifies its inhabitants, but it's all in the name of nothing more than a good night's sleep. It's eventually made clear that she's too absentminded to be actually malicious, so most of the time she doesn't realize that she's harming others or herself.
  • "Could Have Avoided This!" Plot: The plot of chapter 90 involves the princess and Poseidon doing their best to avoid getting flu shots due to their shared fear of needles. At the end, after they're finally caught and given the shots, it's pointed out if they had Hi-Potions, the shots wouldn't have been necessary. Except the Princess drank so many of them that year they didn't have enough and had to resort to the injections, with the realization that their problem was all her fault causing the Princess to earnestly apologize to Poseidon for the incident.
  • Dark Horse Victory: The winner of the Castle's summer festival beauty pageant is Harpie, who went completely unnoticed in the face of the other contestants (the Princess, a slime, a number of zombies, and the men of the Castle in drag, trying to prevent the Princess winning).
  • Death Is Cheap: Thanks to the Demon Cleric's ability to revive the dead, the poor souls the Princess uses for material are generally okay. Heck, the Princess herself has died a few times in her search for a sleeping spot. In spite of this, the mental and physical toll on the Demon Cleric incurred by the Princess is enormous, as she's killed a mountain range's worth of demons on her own. At one point the Princess is shown delivering a laundry basket full of demons she'd killed over the past week to the Cleric for resurrection - with a statement that this is a part of their weekly routine.
  • Embarrassing Old Photo: Chapter 132 sees both the Demon King and Demon Cleric trying to retrieve photos of their embarrassing pasts from the Former Demon King's Castle. Unfortunately, the Princess got there first in her search for high-class bedding.
  • Entertainingly Wrong: At first, the demons believe the only reason the Princess is assaulting them and breaking out is that she wants to escape. It takes a fair while for them to understand that her only concern is getting some rest. This, however, turns into the demons going on logic tangents that involve the princess ranging from her romancing them to hurting them, and always being wrong in said assumption.
  • Failed a Spot Check:
    • Hades manages to completely miss the havoc the Princess causes when she's at his place, including a notable incident where she ripped apart his robes to make pillows - while he was wearing them.
    • The Princess completely misses the creatures that are scaring her in the ghost stories she's reading are herself and the castle demons.
  • Forced Sleep: At one point, the princess casts a high level sleep spell, only for it to knock out everyone in the castle except her.
  • Fountain of Youth: The Princess stumbles on one while looking for something to make her smaller, and it temporarily turns her into a kid. When she tries to replicate the effect, she inadvertently turns all the demons in the castle into kids instead.
  • "Freaky Friday" Flip: The Demon Cleric starts wishing he could become something pure like a Teddy Demon while resurrecting one, which results in him temporarily switching souls with it.
  • Fun Size: A mandrake that grew out of the Princess's head ends up taking on her nature, doing whatever it can in order to have a good sleep. The Princess recognizes they're too similar to live together, and so gives the mandrake to Succyun to look after.
  • Gilded Cage: For all that the people of Goodereste worry about her, Syalis is well cared for by her alleged captors. She eats better than most of the demons do, and nobody ever seeks to harm her. Every injury she suffers is the direct result of her going on an adventure to improve her sleeping conditions instead of staying in the quarters she's supposed to be locked up in.
  • Green-Eyed Monster: The demons get jealous of the Princess getting starry-eyed over the athlete Raikou, and try doing everything they can to catch her attention. She ignores them.
  • Half-Human Hybrid: Narmie is half-human, half-demon.
  • Holy Halo: When the Princess becomes mellow because of the mandrake growing out of her head in chapter 80, the demons imagine her with a halo making hand signs like a Buddha statue.
  • Horned Humanoid: Multiple:
    • The Demon Cleric
    • The Demon King
    • Hades
    • Former Demon King Midnight
  • Horny Devils: There is at least one succubus, but they don't feed with sex, per se. They feed on human vitality, and survive by being popular.
  • Hot Springs Episode: Chapter 39 features the Princess digging a hot springs in the castle basement - flooding a good part of the place in the process, not that she cares. Later on, chapters 97-101 form a hot springs mini-arc, with chapter 97 about the demons getting ready for the trip, chapters 98-100 about what happens at the springs, and chapter 101 about the trip back.
  • Humans Are the Real Monsters: While the demons hold Card-Carrying Villain attitudes, constantly proclaiming themselves evil, as a whole they're mostly harmless, while time and time again it's shown that the humans are much, much worse, even though most of the humans aren't deliberately malicious. For some examples, the Princess is so obsessed with sleep she has a habit of slaughtering demons by the dozen daily in her efforts, while Sir Dawner is so obsessive in his desire to marry the Princess that he borders on being a Yandere.
  • Hypocritical Humor: It takes a while for the Princess to clue in that the things she complains about the mandrake doing are the exact same things she does.
  • Innocent Innuendo:
    • The Princess ends up causing a mass nosebleed epidemic in chapter 40 by asking everyone if they love her (because it was Valentine's Day and she wanted chocolate to help her fall asleep, having no idea what it means when a girl her age asks people if they love her).
    • Becomes something of a running gag, as often the Princess will want something mundane only for it to sound like flirting or even a sexual proposition. Such as the time she wanted to sleep in other demons' beds to see how they feel.
  • Intercontinuity Crossover: Komi Can't Communicate has an omake where the titular Komi finds herself in the castle and meets the Princess, and in true fashion, is captured by the demons for safe measure (though as far as Komi's concerned, it's All Just a Dream), while this series has an omake where the Princess travels to Komi's world for a short while.
  • Kotatsu: Once winter comes around, Syalis goes around the castle gathering materials to make one. In a later chapter, she gets turned into a cat by accident and uses her reduced size as an opportunity to fit her entire body under the kotatsu for a nap.
  • Lima Syndrome: After the Princess gets kidnapped from the demons and returns, it's implied the demons are starting to suffer this, worrying about what'll happen when the Hero finally rescues her. In fact, just the thought that she doesn't like them sends the demons into a massive castle-wide depression. There are also hints that some of the demons may have started to develop romantic feelings for the princess, and a Running Gag involves demons misintepreting her intentions as romantic.
  • Loophole Abuse: In chapter 75, the rules of the demons' impromptu armwrestling tournament state that the winner must pin their opponent's hand to the table for three seconds. The Princess defeats Ice Golem (after... persuading his original opponent to give up his spot) by cutting off his arm and laying it on the table since the rules never said that the hand had to be attached to its owner.
  • Luck-Based Search Technique: Syalis accidentally performs a three stage unlocking process to find the hidden room where an ancient grimoire is stored by falling down the stairs.
  • Merging Mistake: One of the Princess's resurrections sees her accidentally get merged with a demon cat, coming back in its body. The Demon Cleric manages to undo it, but not until after the cat-Princess wrangles him into smuggling her back to her cell to spend several hours sleeping under the kotatsu.
  • Money Spider: Monsters apparently drop gold when defeated in this world. The Princess planned to fund a shopping expedition to the nearest human city with the proceeds from "greeting" monsters and adventurers: her thought bubble shows 10G for a ghost shroud. She falls asleep while waiting in line for a high-tech pillow, forcing her chaperones to borrow funds from demons who lived nearby.
  • Morality Pet: The Princess shows genuine affection towards the eggplant seal, treating it as if it were her child.
  • Non-Indicative Name: While the demons that act as commanders of the demon army under the Demon King are called the "Ten Elders", there aren't actually 10 of them in number. That's just the number of positions available to be commanders in the army. There's actually only 9 of them, though the Princess at times is considered an unofficial 10th.
  • No-Self Buffs: At one point, the princess casts a high level sleep spell, only for it to knock out everyone in the castle except her.
  • Offer Void In Nebraska: While Syalis can watch the human shopping network from the Demon Castle, it's outside their delivery network. Multiple chapters center around the Princess seeking to reproduce some item she saw being advertised there since she can't order it.
  • Our Demons Are Different: Including such things as:
  • Painting the Medium: The plot of chapter 106 involves the Ten Elders (and the princess) drawing a 4-koma manga in order to convince children to join the demon army. The time they spend drawing the 4-koma is depicted in the chapter as a 4-koma, unlike the regular manga style of the rest of the chapter.
  • Pity the Kidnapper: The demons really didn't realize what they were letting themselves in for. The Princess is by far the worst thing they've ever had to deal with, but due to their vested interest in luring the Hero, they are completely unable to rid themselves of her.
  • Poor Communication Kills: The Princess, for all her skill at slaughtering demons, is astonishingly awful at speaking to other people. A number of gags revolve around how she simply goes out and acts, leaving everyone around her with zero context on how to handle the situation. Other times, her actions have too much context, giving everyone around her the completely wrong idea.
  • Potty Emergency: The princess runs into one of these when the usual toilet near her cell is getting changed. She tries finding another toilet, but most of the demons use toilets that she can't use because of their species. In the end, she ends up using the Demon King's private restroom, much to the chagrin of the Demon King, who also needed to use the restroom.
  • Punny Name: The official English name of the human kingdom and its royal family, Goodereste. (This's apparently a Woolseyism, as the original Japanese name is Kaymin, which doesn't translate to 'good rest' or anything similar.)
  • Railroading: The demons actually try to do this to Dawner, as he keeps getting lost on his quest.
  • Retronym: While the manga has the English words 'Sleeping Princess' alongside the title on the tankobon covers, the anime instead has the official English title alongside the Japanese title.
  • RPG-Mechanics Verse: Status conditions, experience points, and item crafting are all mentioned at different points in the series.
  • Schizo Tech: For the most part, the world seems to be a medieval fantasy world. However, things like mecha and nanomachines are apparently pretty common-place.
  • Self-Deprecating Humor: In Chapter 106, when brainstorming ideas for the premise of a propaganda manga, one demon offers up the premise of this manga, only for the Princess to say it sounds boring with no end and another saying it probably wouldn't be very funny.
  • Shout-Out:
    • The Princess' name is Aurora just like the titular character in Disney's Sleeping Beauty.
    • The princess occasionally uses the battle HUD from Pokémon.
    • The people on the recurring infomercial resemble Bianca and Nera.
    • The princess imagines seeing the main characters of My Neighbor Totoro jumping on her bed in chapter 5.
    • One of the classes that the princess dresses up as in volume 3 is a plumber which improves her jumping ability.
    • The Demon Cleric visualises the princess and the cat demon doing the classic Dragon Ball Z Fusion Dance move to merge in chapter 31.
    • When the princess' dream is shown in chapter 77, it resembles the Mushroom Kingdom complete with floating blocks and tall rounded mountains.
    • The Princess in a stack of swim rings in chapter 102 reminds the demons of the Pop-Up Pirate game.
    • Chapter 103 takes its title from Arrietty, the scanlation going with its Disney name and calling it The Secret World of Suyarrietty, and the official translation going with the direct translation of its Japanese name and calling it The Borrower Suyarrietty.
    • The masks the Princess makes for the cafe during the festival arc are copies of Jason Voorhees's hockey mask.
    • One of the classes the Princess dresses up as in volume 10 is a Ghost Buster.
    • Chapter 149's title is The pRINCESS M@STER.
  • Skewed Priorities: Hypnos is willing to overlook nearly any act the princess commits in the name of sleep: Destroying a one-of-a-kind chest to take its fittings as crafting materials, using scarce fuel, slaying a Load-Bearing Boss, none of those is more important than sleep. Or, in this case, crafting a goofy pair of prism glasses that would allow the wearer to read lying down with no risk of dropping the book.
  • Spell My Name with an "S": Is the Princess's name "Syalis", "Suya Rhys", or "Suyaris"? According to the Viz translation, her full name has it as "Sya Lis", but everyone in-universe goes with "Syalis".
  • Stalker with a Crush: Stray Kamaitachi becomes this thanks to his awkwardness around the Princess, with the Demon King watching over him as his guardian. When the Demon Cleric confronts them about it, he realizes he's become one himself.
  • Status-Buff Dispel: At one point the Princess is forcibly equipped with a status cancelling artifact after she gets herself killed using a giant poisonous mushroom as a mattress. To her dismay, this includes the status effect of sleep - even when it occurs naturally.
  • Tickle Torture: The Demon Cleric has let his bats punish the Princess with this when she's annoyed him by dying and requiring resurrection too often.
  • Whole Episode Flashback: Chapter 41 is set in the past, taking place a few days after the Princess first arrives at the castle.

Alternative Title(s): Maou Jou De Oyasumi


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