The Devil King is Bored is a (so far) none-too serious manwah (Korean manga) about the Devil King. As the title suggests, he's bored! Unluckily for his subjects, his entertainment often comes at their expense. Luckily for us, his antics are absolutely priceless! Now follow the Devil King as he seeks out entertainment by tormenting his people, beating his more annoying subjects to a pulp, kidnapping princesses, and making us laugh! Overall, The Devil King Is Bored looks to be a parody of the typical Heroic Fantasy stereotypes that every early Eastern RPG seemed to follow.Translations can be read on almost any major manga site.
While the Devil King is horribly abusive to anyone directly under his command, it's played with in that he's actually a Jerk with a Heart of Gold; he stands up for his subordinates when they're really in trouble (or at least when anyone else is tormenting them). One of his lieutenants also says he likes him because he doesn't make them invade the human realm or fight against angels, so by the standards of Devil Kings he may be better than he seems.
Batman Gambit: The Devil King purposely kidnapped the Princess in the hopes that Heroes would be sent to rescue her.
Blood Knight: The only thing that really gets the Devil King excited is the possibility of a serious fight, to the point where he'll deliberately spare enemies in hopes that they'll be stronger next time. Most clearly visible here, but his desire to attract interesting people to fight is what kicks off the real plot.
Butt Monkey: Mashim and the human king in particular, but really, nearly everyone who isn't the Devil King ends up in this role eventually. (And the Devil King, while he gets to torment everyone, is always bored.)
Cerebus Syndrome: Early on, the Devil King angrily tells Succubus that he told her never to use her dream-controlling magic on him; this is played off as just another joke about him lashing out at his subjects. Later, in chapter 17, we see exactly what dreams she keeps sending him and learn a bit about his backstory in the process, and it's not at all humorous.
Come to Gawk: Parodied. When Mashim has been captured by humans, Succubus invites a bunch of demons to come and laugh at him from outside of his cell.
Comically Invincible Villain Protagonist: The devil king is stupidly strong. In the backstory, the united armies of Heaven and humanity defeated his entire kingdom and every other demon, and still couldn't beat him.
Crystal Dragon Jesus: As it is a parody of early Eastern RPG stereotypes, the story does take cues from Christianity in much the same way that one would expect a JRPG of the eighties or nineties would, only parodied.
Dirty Coward: Priestess Chloe. The Archangel Gabriel himself is shocked at how such a selfish and greedy priestess has so much holy power.
Distressed Damsel: Again, parodied. The only reason the Devil King kidnaps her in the first place is to attract powerful opponents and create some excitement for himself as a result.
Even Evil Has Standards: The Devil King regularly massacres his subjects in order to entertain himself, but when he finds one mortally wounded and is attacked by the ones responsible, he'll star an even bigger massacre!
Jumped at the Call: Also parodied. The heroes, their leader in particular, nearly freak out when they find out that the Devil King has kidnapped the king's daughter and, due to extenuating political circumstances, cannot send a full-scale army into hell to rescue her, and that they've been selected to go save them. The look on his face has to be seen to be believed.
Lethal Chef: The princess. She's so bad that when she cooks for her father, he thinks she's trying to kill him. Her cooking is amazing to demons though.
Noble Demon: Surprisingly, the Devil King. He says that the humans who entered through the portals he entered were his guests, which is why he always sent them back alive after beating them; humans who sneak in without following the rules don't get that respect.
Reality Ensues: One chapter shows what happens when the human king tries to act the way the Devil King does, without his ridiculous personal might. It doesn't go well for him.
The Starscream: Mashim, otherwise known as "Number Two" is a Devil that constantly tries to take the current Devil King's place. Sadly for him, he's a supreme Butt Monkey and can never get away with anything.
Throw the Dog a Bone: After nearly 29 chapters of being relentlessly tormented and treated as a butt-monkey, often by the Devil King himself, the depowered Mashim finally gets a chance to shine when the Devil King arrives and immediately restores his powers.
Wrong Genre Savvy: The Princess is convinced that she's in a Love Triangle romance story between her, the Devil King, and a hero (who she hasn't even met yet.)
Xanatos Gambit: Pulled off by the Red Devil after he's become friends with a human girl and convinced that this girl has been kidnapped. If he rescues her, then everything's fine, but if something happens to him, the Devil King shows up!