The series opens as Angel Trainee Flonne descends into the Netherworld in front of a burning castle in the middle of a lake of lava, having been sent to assassinate the Overlord. Skip to two years later, she still hasn't found him, and heads into what she believes is a tomb to take shelter. Here, she falls through the floor and discovers herself in a garbage heap — why it's there is never explained, but she forgets all about it after spotting a coffin with the Overlord's crest on it. Hoping she may have found her target at last; she cracks it open, only to be disappointed that it contains a young demon, not her target. Introducing himself as Prince Laharl, he is startled to discover his current resting place and that it's been two years since he went for a nap. After some... misunderstandings, he is reunited with his father's former vassal Etna and her personal squad of Prinnies. Accompanied by Flonne, who doesn't think she can go back seeing as how her target actually choked to death shortly before she arrived in the Netherworld in the first place and wants to see if demons are truly as evil as they claim to be, the trio (and the Prinnies) set out for the Overlord's Castle, seeking to place Laharl back on the throne that is rightfully his.
After finally getting the throne back, a new problem pops up when a giant space fleet arrives from Earth's dimension, seeking to lay waste to the Netherworld and conquer it. Laharl, not one to put up with this sort of thing, puts an end to their plans and discovers they were manipulated into it by Vulcanus, of Celestia. Hijacking their flagship for added insult to injury, he pilots it off to Celestia to show them what he thinks of this.
This show contains examples of:
- The Anime of the Game: Of Disgaea: Hour of Darkness.
- Action Girl: Unlike in the games, Etna is less this and more a Faux Action Girl.
- Adaptational Badass:
- The Astro Cannon. While certainly a powerful weapon in the game, it was nothing more than an oversized Dark Cannon, a giant turret, and did nothing particularly special. In the anime, it's a Wave-Motion Gun powered by a shard from Celestia. While Laharl is able to disable it, it's one of the few things Laharl is unable to tank.
- The Earth Defense Force themselves. While Laharl is able to make quick work of many battleships in both the game and the anime, the most they are able to do in the game is make a lot of noise. The anime makes them a far more effective threat.
- Adaptation Explanation Extrication: Laharl and Flonne's fate in the ending was a combination of the normal ending and good ending, in which Laharl spares Lamington and sacrifices his life to bring Flonne back. In the game, it makes sense because of them have gone through several scenes of Character Development, most notably Laharl finally calling Flonne by her name after spending almost half the game calling her "You" or "Love Freak". The anime's focus on comedy, however, meant they lacked the developing chemistry that made that scene powerful in the first place.
- Affably Evil: Even if Vulcanus committed wrongdoings without remorse, he sure acts like a sophisticated gentleman towards Gordon and his group in the second episode.
- Ascended Extra: Sardia was merely a palette swamp of the Magic Knight class and one of several enemies vying for the throne in the game, being defeated in a single stage and not being heard from again. The anime gives her a slightly different design (She has a ponytail and a modified outfit) and is shown to be rather wealthy and sophisticated demon.
- Blackmail: Why Etna works for Maderas, with a slight difference from the original game
- Bad Boss: Etna, Maderas
- Big Eater: Laharl. Perhaps that's how he puts so much power into his Overlord's Wrath spells.
- Butt-Monkey: Prinnies, dood! And Vyers. And Gordon and his squad
- Camp Gay: For whatever reason, Maderas has his more sinister Manipulative Bastard personality dropped and acts disturbingly more effeminate. Still quite manipulative, though.
- Canon Foreigner: Maharl and the King Darth Blink the III, though Maharl is based off of a character design that Takehito Harada, the main artist for the series, made, but never got around to using. Quite a few background demons are not based on any of the demon classes as well.
- Cape Wings: One of the forms Laharl turns his scarf into.
- Card-Carrying Villain: Laharl, and most every other demon as well.
- Catchphrase
- Prinnies:Dood!
- Sardia: Maybe... Maybe not.
- Flonne: The seeds of love are finally blooming in Laharl's heart!
- Clothing Switch: Etna and Flonne get this and a personality switch.
- Death as Comedy: King Krichevskoy, at least at first. Laharl reads in a newspaper that his father died choking on his afternoon snack, in brightly-lit office, in the middle of the day. Laharl has an Imagine Spot of the scene, and laughs.
- Double Entendre: Etna has a blatantly innuendo-filled conversation (that we only hear the final part of) with Flonne in about the 4th episode. In fact, Etna does this a lot.
- Dub Name Change: Inverted. The boar demons Hoggmeiser and his son (Referred to as Porkmeister in the Updated Re-release and later games) are referred to as Zenisky and Koganesky, which are their names in the original Japanese version of the game.
- Fan Disservice: When the Defenders of Earth get a temporary job at a saloon, Gordon ends up in the same white and pink mini-dress as Jennifer, complete with similar close-ups to his assets.
- Fanservice with a Smile: Jennifer gets a temp job in a saloon in a white and pink minidress.
- Groin Attack:
- In a conversation Etna has with Flonne after they start traveling together, she mentions that she gave an unidentified nosy guy a very firm kick in the "you know where" (Flonne doesn't know where, though). It's based on a similar conversation they had in the game's fifth episode.
- And then a couple of episodes later, she pulls one off on an EDF soldier to which Flonne says, "Oh, so that's what you were talking about!"
- Goldfish Poop Gang: The Defenders of Earth get turned into this after the second episode, regularly trying to face Laharl only to be blown away second later.
- Hammerspace: Laharl stores his (rather large) sword inside his scarf.
- Humongous Mecha: Pringer X. Unlike the superboss that appeared in later games, this one is based on the less intimidating robot that Etna introduced in one of her On the Next segments.
- Knight of Cerebus: Just like in the video game, General Carter, the boss of Kurtis. It's even more obvious here as there are few serious scenes prior to the EDF invasion compared to the game.
- Large Ham: Not just one but almost EVERYONE!.
- Laughably Evil: Laharl, since this is a comedy anime. Also, Vulcanus in Episode 3.
- Lethal Chef: Flonne tries cooking for the group in the episode that loosely homages the Prinny World location. Laharl takes a few bite and is sick... although, given Laharl is a Card-Carrying Villain who gets freaked out by people just talking about love, peace and joy, and the fact he sprouts a thought bubble in which he is running playfully through a field of flowers and laughing with joy, it could be just that Flonne's food is so chockful of her positive attitudes it's unpalatable to him. But, then again, Flonne states she's never actually cooked before/isn't a very good cook when Laharl demands she make him something to eat.
- Etna also tries it after Laharal states how bad it is and and also turns blue in the face. It is likely genuinely that bad. Also, Laharl orders Etna to cook something at this point, but she claims her cooking would be worse.
- Long Lost Sibling: Maharl is apparently this.
- Love Freak: Flonne.
- Made of Iron: Laharl. He was poisoned, and instead of dying (like anyone else in the world would have), he slept it off for two years. He can also hold onto Flonne's pendant, which would burn most demons rather badly, but Laharl takes it like a champ.
- Mythology Gag:
- This series could really be considered more of an Alternate Continuity that happens to reference lots of elements from the original game. For example, Maderas calls up a pack of busty (if chastely dressed) succubi and catgirls who start chanting positive phrases like "eternal love", which makes Laharl so freaked out he can barely fight. This is a loose adaption of a background effect from an actual fight in the game, which has the effect of cutting Laharal's attack stats by 50%.
- Pringer X was based on a fictional robot that Etna introduced in one of her On the Next segments. It differs from the smaller yet more intimidating superboss of later games.
- Paper-Thin Disguise: Etna and Flonne dress up in Prinny suits to sneak into Prinny World. They didn't have enough money to get Laharl a whole suit, so they gave him a hat. The actual Prinnies note that Laharl doesn't have the usual Verbal Tic, dood, and call him out on it... so the girls cover for him by saying he's sick.
- Parody Sue: Maharl, "sister" of Laharl.
- Pen-Pushing President: Etna becomes this after becoming Overlord. It's hilarious considering her normal personality.
- Personality Swap: In the Netherworld Hall of Treasures, Flonne and Etna swap personalities (and outfits) due to something that Vulcanus set off.
- Perverse Puppet: It turns out Maharl is actually a puppet in the shape of a demon vaguely like a female Laharl. The "doll" she carries everywhere is actually the real demon animating her and using her as a cover. Though this doesn't stop her getting up and walking around on her own in one scene in one of the last episodes.
- Pretty in Mink: Maharl wears a fur trimmed coat, in a matter just to make her look cuter.
- Ridiculously Cute Critter: Yeah, dood!
- Road Cone: The ending is a mix of the game's Good and Normal endings: Laharl spares Seraph Lamington's life, declaring it's what Flonne would have wanted, then uses up his life force to resurrect Flonne as a Fallen Angel, only to reincarnate as a Prinny.
- Running Gag: Flonne gets most of them. She tends to fall flat on her face rather often, and her cooking is not very good. There's also Vyers, who gets depressed over eventually referring to himself as Mid-Boss... on two separate occasions.
- Shamu Fu: Replaces the daggers and bombs as the Prinnies' weapons.
- Stupid Sacrifice: There doesn't seem to be any reasons as to why Kurtis had jump off the spaceship while holding the bomb, killing himself in the process, instead of just tossing it overboard, except because he's supposed to die in the original game.
- Tentacle Rope: Thursday when programmed to do evil grabs Etna and Flonne.
- This Cannot Be!: Vyers' reaction in the second episode when Laharl calls him Mid-Boss for the first time. Follows it up afterwards with some Angrish and then a This Is Unforgivable!.
- This Is Unforgivable!: Often played for laughs, like in Episode 2 when Vyers says this to the protagonists for nicknaming him Mid-boss just like in Disgaea 1 and in Episode 3 when Vulcanus says this upon seeing Flonne's change in personality while she's sleeping with Laharl and Etna and attempts to kill her only to fall right into a clam instead.
- The only time this trope is played seriously is in the finale when Etna says this to Seraph Lamington for the punishment he gave Flonne for killing some of her fellow angels. Then again, anime are really good with this trope.
- Too Dumb to Live: The Prinnies. They're not too bright in general, but it becomes most obvious when they attempt to establish their own home, Prinny World, on a small floating island... which begins to sink after too many Prinnies show up. They also didn't notice that the loud-mouthed, almost-naked kid with a giant Prinny hat and no Verbal Tic actually wasn't a Prinny.
- Trailers Always Lie: The two promotional trailers for the anime seemed to stay closer to the source material and even hinted that there would be a battle between Laharl and Baal. None of that appeared in the anime.
- At the end of each episode, Etna breaks the fourth wall to make up elaborate and dramatic claims about what the next episode will be (Much as she did in the game). They're pretty much all lies, though some slivers of truth do get through on occasion. Sometimes, the other characters get involved as well, replying to Etna's claims.
- A Twinkle in the Sky: Gordon and his crew get knocked around this way occasionally.
- Verbal Tic: Prinnies, dood!
- Villainous Breakdown: When Vulcanus learns that he was himself an Unwitting Pawn in Seraph Lamington's plans, he goes bat-shit insane and starts laughing evilly while at the same time assuming that Laharl, Etna, and Flonne have taken over his superior's mind. He then becomes The Starscream and pulls out a sword and tries to kill Lamington to show how pathetic and beyond-redemption Vulcanus himself is - all in an effort to prove that what he believes is truly right. He fails, of course, and Lamington punishes him by turning him into a frog - which is both hilarious and satisfying to watch, really.
- We Buy Anything: After raiding several castles for loot, Laharl walks into the nearest general store, and...Laharl: I wanna hock all this crap!Mannequin Shopkeeper: *buried under loot* Yes, sir...
