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Koizumi Yuta is a 14 year old boy who has quite a bit of a problem. The demon princess of the magical world, Lucia, has to procreate with him. That child would have the ability to engulf the entire world in fire for seven whole days. Mikamoto El and Kasukabe Rie are the two angels assigned to make sure that doesn't happen. Kasukabe Rie happens to be the girl he likes. Just how is he going to survive this ordeal?
This is a manga by Seo Kouji
, author of Suzuka
and Kimi No Iru Machi
Princess Lucia provides examples of:
- Absurdly Youthful Father: Yuta is technically the "parent" of the Demon Beasts Children as they call him "daddy". Lucia would fit as well if she wasn't Really 700 Years Old.
- ACME Products: El is always seen shopping at an angel store, though most of the products don't work the way she plans. Though this could be because the one that owns the store is actually a demon and devoted servant to Lucia's family.
- Always in Class One
- Ambiguously Gay: Mary (revealed to be a guy) states to Yuta he does not have any interest in women.
- Ambiguous Gender: It is hard to tell whether Behemoth is a boy or a girl. Though by Chapter 29 she is wearing a bikini so its safe to assume she is a girl.
- Awesome, but Impractical: Bezzle's giraffe style in the Mixed Horse Fighting, despite giving her a height advantage it is impossible to balance.
- Bad Liar: Lucia, usually lampshaded by other characters.
- Beach Episode: Chapters 3 and 4.
- Berserk Button: Do not hurt Yuta in front of Lucia, or you will regret it.
- Betty and Veronica: Lucia and Rie
- Biggus Dickus: Levi claims Yuta's "boob down there" is big.
- Then it is revealed that Mary has one twice as big as his.
- Big "NO!": 
- Breaking the Fourth Wall: The first page of Ch 28 has it where Lucia states they have to hurry since there is only 13 pages this chapter.
- Bribing Your Way to Victory: Bezzle bribed the referee to allow her Giraffe style in the mixed horse fight.
- Can't Hold His Liquor: Rie, who with a single drop of alcohol will change into her Desire Form as well as be completely drunk.
- Catch Phrase: "Levi's a Genius" (not really)
- Children Are Innocent: Despite Lucia wanting to sleep with Yuta, she has absolutely no experience and often stops herself because of it.
- As well as the three Beast Children Behemoth, Levia and Ziz.
- Clothing Damage: A common occurrence in the manga.
- Though in Lucia's defense, she was trying to kill them.
- Covert Pervert: Rie who's feelings of jealousy and lust are suppressed by the glasses she wears.
- Crash-Into Hello: Yuta is forcefully made to do this to Bellze by her servants.
- Crossdresser: Mary is revealed to be a guy who dresses up as a woman. Oddly he will still be dressed as a woman when dressed up as a man.
- Crossover: Princess Lucia shares the same universe with Kimi No Iru Machi, showing that this story's current timeline is during just after Kimi No Iru Machi ended. Also due to this, this story shares the same universe as Suzuka.
- Death Glare: Every guy towards Yuta with his Unwanted Harem.
- Double Standard: Rape, Female on Male: Lucia tries to "make a child" with Yuta every change she gets.
- Though in her defense she doesn't really want to personally. Even expecting El and Rie to stop her before it ever gets too far.
- Easily Forgiven: Camael and her forces. Despite having no calms about killing everyone on that island, after their defeat Yuta and the other demon girls quickly lend a hand to help them. Though it did give Camael a different viewpoint on the idea to Humans, Demons and Angels cooperating.
- Easy Amnesia: Levi
- As well as everyone else by the angels to usually cover up their activities.
- Enthralling Siren: Mary (though is unaware of this). The angels seem to use his voice to lure out demons.
- Everything's Better with Princesses: Lucia the Princess of the Demon World.
- Eye Beams: Lucia does this to prove she is a Demon to Yuta, and towards anyone who annoys her.
- Eye Scream: Lucia and Bellze servants poke Raguel's eyes out, through his glasses.
- Fantastic Racism: Rie informs Yuta that angels are taught to believe all demons are evil. But she herself is beginning to question that the more time she spends with Lucia.
- Fish People: Levi in human form.
- Green-Eyed Monster: Lucia seems to get this way every time Yuta is seen with Rie.
- Half-Human Hybrid: Pretty much the goal of the demons is for Lucia to have a child with a human.
- Happiness in Slavery: Bellze highly powerful demon servants truly care and wish to serve her. In one case when they were nearly killed by Lucia, one of her servants hoped that when she is reincarnated she could come back to serve her.
- How the Mighty Have Fallen: Bellze says this word-for-word about Lucia's predicament.
- Hypocrite: The Angels. They are supposedly supposed to protect humans from demons, but that sure hasn't stopped them from attempting to kill humans. One did voice concern for killing a human and children, but only because she was worried about becoming a fallen angel and the other angels laughed at her for worrying about that.
- Hypocritical Humor: Bellze states she wants to show her feelings to Yuta without being forceful. After finding out that he went on a vacation trip with Lucia she orders her servants to shutdown all transport systems and to take him by force.
- Lucia does this too at the vacation. She tells Levia and Behemoth to behave and not jump on the bed. But after Yuta suggested that he would make dinner for them, Lucia goes and jumps on the bed with the kids.
- Improbably Female Cast: Yuta is essentially the only main male character with the amount of named male characters can be counted on one hand. There is pretty much 20 females per male seen in this manga.
- Innocent Fanservice Girl: Levi has no qualms of walking around completely naked.
- Invisible to Normals: A Devil's horns and tail are invisible to humans that were not born on said date, making them pass off as normal humans.
- I Read It for the Articles: Yuta states he only uses porn magazines for reference material for his drawings.
- I Was Just Joking: When Yuta states he was drawing all night, El suggests he was actually looking at porn magazines all night. Yuta believes she was peeping on him again where she replies she was just kidding then states making fun of him for reading them. He explains, quite nervously, that he uses them for reference material.
- Knight Templar: The Angels appear to be this towards the Demons, even being raised to believe that all demons are evil. Rie and El even fully believed that Lucia was just using Yuta. It took some time to realize that she, and by extent many other demons that show up, were not anywhere as evil as they were taught, to the point they have formed a bit of a villainous friendship with each other. Rie and El are now deliberately not informing the higher ups that they have come across demons because they know full well of what they will do.
- Lady Looks Like a Dude/Dude Looks Like a Lady: The popular singer Mary goes to school disguised as a boy. It is later revealed that Mary is actually a cross-dressing man, disguised as a man.
- Land, Sea, Sky: The Three Demon Beast Children: Behemoth for Land, Levia for Sea, and Ziz for Sky.
- Loophole Abuse: In a very heartwarming way. Why doesn't Rie want to inform the higher ups about Levia and Lucia? Because it is against the rules of an Angel to break up a happy family.
- Love Potion: Lucia tries these on Yuta with mixed results.
- Makes Just as Much Sense in Context: Mary is man who dresses up as a female and is a popular singer. So when he attends school he still dresses up as a female, but then disguises that female outfit with an additional male outfit to pose as a male... while he is already a male.
- Meaningful Background Event: At the end of Chapter 18 when Rie and El walk into Lucia's ramen shop to find all of the demon girls naked and on top of Yuta, you can see Rie's glasses crack. The next chapter reveals that her glasses actually suppress her feelings of lust and jealousy to which have been building until they cracked from the sight.
- Missing Mom/Disappeared Dad After the Angels tricked Lucia's father out of his land, her mother ran away.
- Yuta's dad has yet to be mentioned.
- Also Levi's mother vanished.
- Moment Killer: Expect one every freaking time one of the girls are alone and starting to finally get close to Yuta.
- No Guy Wants to Be Chased: It takes a while for Lucia to realize that her trying to sexually force herself onto Yuta is actually doing more harm than good on trying to get close to him.
- Not What It Looks Like: At least every chapter.
- Number of the Beast: Yuta was born June 6th of the 6th year of Heisei, at 6:06:06 am.
- Oblivious to Love: Yuta doesn't seem to realize that Lucia or Rie have true feelings for him. As he believes Lucia's affection is a result of her father wanting her to have a child with him, and Rie's affection are due to her duty to protect him.
- Taken Up to Eleven in Chapter 19 when Rie succumbs to her desires strips bare naked and confesses her feelings for him, he STILL DOESN'T GET IT!!!
- The Ojou: Bellze is referred to this by her servants.
- Older Than They Look: Lucia states she is 100,014 years old.
- Unknown for El and Rie, however they have been watching over Yuta since he was a kid. Although Rie is at least old enough to have destroyed Sodom and Gomorrah which was in 3000 BC.
- The Art Club Adviser Shiori Houjou looks like a grade schooler. And despite wanting to be treated like an adult, she defiantly doesn't act it.
- Open-Minded Parent: Yuta's mom seems to have given her blessing for Yuta to be with Lucia in a sexual way. She often comes up with some reason to leave the house and leave Yuta and Lucia alone every time Lucia comes over.
- Even later with El, Rie and Lucia with Yuta at the same time, commenting "It is better if boys are energetic."
- Our Angels Are Different: Rie seems to believe that Lucia, the princess of the Demons, is more pure than the angels.
- Our Demons Are Different: It would appear all that is left of their domain is that Ramen Shop.
- Parental Abandonment: Lucia's mother left her and her father.
- Precision F-Strike: Lucia when she is especially angry.
- The Promise: Yuta promises Lucia that he will be her friend. Later Rie, revealing herself to be an angel and telling him that she will be with him if he cuts all ties with Lucia, he rejects her offer due to this promise.
- Really 700 Years Old: Lucia, being 100,014 years old. Doesn't stop her from acting like a 14 year old though.
- Rich Bitch: Bellze
- Running Gag: El always seems to appear right behind Rie.
- Satan: Lucia's dad
- Shipper on Deck: Rie seems to have an interest in Lucia's and Yuta's relationship, deliberately preventing her higher ups from knowing a Demon has made contact with him just to see how the relationship turns out. Despite her own secretive feelings for him.
- Sick Episode: Chapter 11
- Sleep Cute: Lucia, which is what made Yuta see that demons were not evil.
- Snow Means Love: Maybe not "love", but Yuta seems to have gotten closer with Lucia after their time at Fantasy Land when it started to snow. At first he wouldn't even consider holding hands but afterwards he doesn't mind having her hold onto his arm.
- Spit Take: You would too when you found out the fish stock is actually Levi's bath water.
- Super Strength: All the Demons and Angels have shown this.
- Yuta, a side affect of the Love Potion that caused him to hug a tree in half.
- Sympathy for the Devil: You just can't help but feel bad for how Lucia's family turned out.
- Third-Person Person: Levi
- Title Drop: Usually someone says the name of the chapter in each chapter.
- To Be Lawful or Good: Rie seems to struggle with this at the beginning, knowing that she is a Angel she shouldn't be helping Yuta and Lucia staying together but she knows that she isn't as bad as she was taught to think.
- Tomboy and Girly Girl: El and Rie.
- Tomboy Princess: Bellze refers Lucia as one.
- Truth Serums: Levi gives this to Yuta under the belief it is medicine that will get rid of his cold. He tells Lucia he was glad that she game to look after him while he was sick, but she mistakes this as the affect of another medicine Levi also gave him.
- Tsundere: Lucia
- Unwanted Harem
- Villainous Friendship: Between Lucia and El. Rie is only against Lucia because of her being a demon, but when that isn't involved she is usually nice to Lucia.
- What Happened To The Angel: On some chapters it will have it to where normally El and Rie would have stopped it long before it got that far, even Lamp Shaded by Lucia at one point. Often the very last panel of the chapter shows that they were distracted by something else at the time, usually they were out shopping.
- Wise Beyond Their Years: Yuta, if they didn't focus on his age you would assume he was at least 16-17.
- Wounded Gazelle Gambit: Bellze Servants do this when Lucia threatens them here.
- Wrong Genre Savvy: Camael fully believes that the reason all the demon girls are with Yuta is because they are planning to amass an army and will soon be attacking Heaven. After she is defeated El and Rie show her she was wrong.
- You Gotta Have Blue Hair: El has blue hair.
- Younger than They Look: Yuta, despite looking and acting somewhere to his late teens, he is only 13 years old.