[[quoteright:226:http://static.tvtropes.org/pmwiki/pub/images/fdsaf_ahye_rhre_2226.jpg]]
[[caption-width-right:226: [[HoYay Gay]] or just student and teacher? The world may never know.]]

->''"You will rule in terror whether you like it or not!"''

''Demon Diary'' (마왕일기, mawang ilgi) is a {{manhwa}} by writers Chi Hyong Lee (vol. 1) and Yun Hee Lee (vols. 2-7) and artist Kara.

A young thief called Raenaf is discovered to be the successor of Demon Lord Raenaf IV, and all of the dark powers and responsibilities that come with. The problem is that Raenaf's personality is exactly the opposite of what is expected of a Demon Lord: he's innocent, careless and utterly clueless. Eclipse, a demon of the highest order and previous vassal of Raenaf IV, is charged with teaching Raenaf V to become the ideal Demon Lord.

Fans of this title have hotly debated whether ''Demon Diary'' is about a tender teacher-pupil relationship or is boy's love (Shounen Ai / {{Yaoi}}). Read it and decide for yourself.

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!This manwha provides examples of:

* ActuallyThatsMyAssistant: happens ''repeatedly''.
* AttentionDeficitOohShiny: Raenef's attention is like a wandering butterfly caught in the middle of a war zone. It flies very erratically and doesn't survive long.
* BadassBookworm: Raenaf IV possessed no natural magical talent. But he ''was'' good at studying the use of incantations to get around that hurdle.
* {{Bishonen}}. Lots.
* CampStraight: Krayon.
* TheChessmaster: Raenef IV. Though he couldn't wreck havoc in the traditional Demon Lord way (e.g. throwing around lots of destructive power) he ''did'' manage to make his mark by teaching simple offensive magic to humans, leading to wars that would claim millions of lives. [[spoiler:He also masterminds ThePlan that passes his knowledge and power onto a successor]].
** Ranef (V) eventually takes after him in book 7, [[spoiler: initiating his own plan that results in the recombination of his original personality with Raenef IV's knowledge and intellect, which were originally split due to the time distension]].
* TheComicallySerious: Eclipse.
* CrouchingMoronHiddenBadass: Chris. He's actually quite talented and immensely powerful. If he can remember the incantations correctly, or if he stops stroking his ego long enough to pay attention to the situation... Let's face it, he's an idiot 95% of the time.
* FeeFiFauxPas: Raenaf's first meeting with the other Demon Lords ends badly because he can't comprehend basic etiquette.
* GeniusDitz: Raenef. He is the living personification of ditzyness... but he is actually very powerful. This is part of the problem, considering the kind of damage he does if he gets distracted in the middle of doing something magical and leaves it hanging in the air.
* IKnowYourTrueName: An important concept in the story is the use of "true names" in the use and inheritance of magic. This is how Raenaf was able to inherit the power of Raenaf IV despite having no relation. [[spoiler:A curse that threatened to destroy Raenaf IV's True Name is what spurned the story into action [[EvilPlan as the whole plot was guided by Raenaf IV to sidestep the effects]]]].
* {{Keet}}: Raenef.
* LetsGetDangerous: All things considered, Erutis is one of the weakest members of the main cast (having no innate magic powers to throw around). But when provoked, she won't hesitate to show you why she's considered a "swordmaster"...
* MyDeathIsJustTheBeginning: [[spoiler:Raenaf IV]].
* NoSocialSkills: Raenaf, mainly due to his complete inability to read situations, or understand what's going on in general.
* OurDemonsAreDifferent
* OurMonstersAreDifferent
* PunchClockVillain: A lot of the Demon Lords seem to fall under this, committing acts of great evil because it's ''expected'' of their position.
* RetiredBadass: Eclipse. Also Chris's mentor. They both seem to remember the good ole' days when they weren't responsible for their idiot charges.
* SexyMentor: Eclipse.
* SplitPersonality: [[spoiler: Raenef. Due to the huge trauma of being pulled back from a ridiculously far distant future inducing a fracturing of his personality.]] He recovers, though, [[spoiler: when his personalities are integrated, resulting in the same Raenef, but with a sharper intellect and a ''much'' expanded vocabulary]].
* StalkerWithACrush: Krayon for Erutis. Unfortunately for her... And the people around her when she gets pissed at Krayon and goes for her sword.
* TooDumbToLive: Raenef. Lampshaded by everyone ''including'' the author.
* TookALevelInBadass: [[spoiler:Raenaf, after Raenaf IV finishes ThePlan]].
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