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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.

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



  • A Million Is a Statistic: Princess Syalis has killed demons by the millions during her captivity without ever batting an eye.
  • Animal Motif: The princess has a bear motif, as shown by her association with the teddy demons, her bear print panties, her habit of sleeping all the time, and her murderous rampages.
  • Anthropomorphic Personification:
    • The spirit of the grimoire Al Azif manifests as a young boy in Ancient Egyptian-style clothing.
    • Morpheus describes himself as being like the embodiment of sleepiness.
  • 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.
  • Advertisement:
  • 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).
  • Beary Friendly: The Teddy Demons, which're pretty much teddy bears with wings that are the universe's version of The Goomba. The Princess tames them early on with her brushing technique and sometimes involves them in her schemes to fall asleep.
  • Butt-Monkey:
    • Almost every demon in the castle qualifies when it comes to the Princess, but it's the ghost shrouds that get her punishment the most. As animated beings of fabric, the Princess finds them ideal for textile purposes, so she has little inconvenience cutting and shredding through them for bedding, clothes, and almost anything she can muster. Almost every appearance of a ghost shroud ends up in the Princess using it for something. Second place among the demons is the poor, overworked Demon Cleric, who has to heal and/or revive all the demons that Syalis kills and maims.
    • Poor Sir Dawner is this during his quest, as the items and opponents he's supposed to face go awry and way out of his favor due to the Princess's efforts or the Demons' blunders.
  • 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 Demons make certain she never learns who actually won (or that the winner turned the pod into a bobsled).
  • 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.
  • Cute But Psycho: The Princess is so cute when she finally sleeps you might be able to ignore all the demons she imprisoned, enslaved, maimed, and/or killed in order to get everything just right.
  • 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.
  • The Dreaded: As shown in one chapter with a baku responsible for purifying everyone's dreams, the princess is literalinvoked Nightmare Fuel to the denizens of the Demon Lord's castle.
  • Emotionally Tongue-Tied: Stray Kamaitachi has a crush on the Princess, and as a result gets tounge-tied around her.
  • Everyone Calls Him "Barkeep": While the Princess does have a proper name, she is almost exclusively referred to as "Princess". Even when her name is brought up, she's usually referred to by her middle name of Syalis rather than her first name of Aurora. Similarly, most everyone calls the Demon King by his title, apart from Poseidon's elder brother Hades, who calls him Twilight.
  • Exotic Eye Designs: The Princess has stars in her eyes, which the volume 1 extras state is the mark of the royal family. Al Azif, meanwhile, has pentacle-shaped pupils.
  • 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.
  • Fountain of Youth: The Princess stumbles on one while looking for something to make her smaller, and it temporarily turns her into a kid.
  • Friend to All Children: About the only demons safe from the Princess are either really small and cute or are children.
  • Fun Size: A mandragora 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 mandragora 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.
  • Goofy Print Underwear: The Princess typically has knitted wool bear print panties for cold weather.
  • Hero of Another Story: The efforts of the hero Sir Dawner to rescue the Princess mainly occur in the background while the story focuses on Syalis' efforts to improve the living conditions in her quarters while in nominal captivity. He eventually catches up to her late in the series, but is pretty much told by the rest of the demons that his presence and efforts were All for Nothing and that she doesn't want to come home at all. He refuses to let that stop him, deciding to press on and change her mind.
  • Horned Humanoid: The Demon Cleric, Demon King and Hades.
  • Horrifying the Horror: The residents of the Demon King's Castle have nightmares about the Princess. She really couldn't give a shit. She is more terrifying than all the demons in the castle combined.
  • 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.
  • Hypocritical Humor: It takes a while for the Princess to clue in that the things she complains about the mandragora doing are the exact same things she does.
  • I Just Want to Have Friends: Poor Harpie just wants to have human friends. Unfortunately for her, the only human around is the princess, whose sole interest in her is that her wings can be used as a down comforter.
  • Idiosyncrazy: Everything the Princess does is in the name of getting a good night's sleep. Escaping? Getting rescued? Making friends? She couldn't care less. She just wants a nice comfy sleep.
  • Improbable Weapon User: Syalis' default weapon is a giant pair of scissors, which she primarily uses to slaughter ghost shrouds so she can use their bodies for fabric.
  • 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.
  • Jerk Ass: The Princess is hands down the most evil person in the manga.
  • Killer Rabbit: After making pajamas out of Teddy Demon fur, The Princess becomes a type of subspecies Teddy Demon that the others can call on when in trouble.
  • 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.
  • 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.
  • Mundane Utility: The princess is a master of taking powerful weapons, sacred artifacts, and even an ancient book of incredibly powerful magic and using it all to just try and make her room perfect for sleeping.
  • Nice Girl: Harpie is about the sweetest character in the manga.
  • 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.
  • No Sense of Direction: The Hero's apparently had a terrible sense of direction since he was young.
  • Oddball Doppelgänger: Succyun the succubus looks remarkably like the Princess, but where the Princess is focused on sleeping, Succyun wants to become more popular (since succubi feed on human vitality, and so need to be popular to survive). Unfortunately for Succyun, she didn't fully appreciate the Princess's true nature until the Princess had become attached to 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.
  • Older Than They Look: Despite the Princess's childish appearance (and behaviour), she's old enough to have significant administrative duties at home. This is driven home when she asks just how old the demons think she is after being handed a pile of children's homework. She implies that the workload is part of why she's so obsessed with sleep, since she wasn't allowed to sleep until her duties were complete (and since she has no official duties while a hostage other than to remain in the castle until rescued or ransomed, the only thing she can think of to do is sleep).
  • Our Demons Are Different: Teddy bears with wings, literal Bed Sheet Ghost, a humanoid pile of car tires? Yup.
  • 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.
  • Play-Along Prisoner: It becomes pretty clear that the Princess is a hostage in name only, and could leave anytime she felt like it. After a while she even gets a flying machine, and the only thing she uses it for is to commute to various places to search for more sleep-enhancing items before coming back instead of trying to go home.
  • 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.
  • Really Fond of Sleeping: The princess. It's her most defining characteristic.
  • Requisite Royal Regalia: Syalis trades her crown for a pair of scissors in the second chapter (she can't sleep with it on without it marring her skin, and she needed the scissors to cut cloth to make new bedsheets). But since she is still a princess, and she needs to keep her hair out of her eyes, she makes a hairband in the shape of a crown and wears that from then on.
  • RPG-Mechanics Verse: Status conditions, experience points, and item crafting are all mentioned at different points in the series.
  • 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.
  • Shaggy 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.
  • Shout-Out:
    • The princess occasionally uses the battle HUD from Pokémon.
    • The people on the recurring infomercial resemble Bianca and Nera.
    • 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 the Disney name and calling it The Secret World of Suyarrietty.
  • Silk Hiding Steel: The demons have absolutely no defenses against the Princess, and it's shown time and time again that they're at her complete mercy... and she's just a young girl.
  • 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.
  • Spanner in the Works: The Princess is messing up the Hero's quest, and the Demon King's plans for a climactic battle, by appropriating/destroying magical artifacts intended for the Hero.
  • 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".
  • 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.
  • Super Drowning Skills: The Princess doesn't know how to float or swim, and when the demons try to teach her, she can only manage to swim a few metres.
  • Too Dumb to Live: The Princess doesn't have much in the way of common sense, and has died a few times because her need for a comfy sleeping spot outweighed her sense of self-preservation.
  • Unfortunate Names: The Demon Cleric is deeply, deeply embarrassed by his real name, because he shares it with a demon who holds indecent feasts with witches.
  • Weight Woe: The Princess is not pleased to be told she's gotten fat during the New Year celebrations, and starts trying to slim down.
  • Whole Episode Flashback: Chapter 41 takes place a few days after the Princess first arrives at the castle.
  • Workaholic: The real reason why the Princess won't come back. She worked day in and day out for her subjects from her home country (who did and still do adore her), but eventually she grew tired of her growing pile of work and sees her kidnapping as an opportunity for relaxation she hasn't gotten in a long time.

Alternative Title(s): Maou Jou De Oyasumi


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