is a tactical role-playing video game developed and published by Nippon Ichi Software for the PlayStation 2. Set in a world full of demons and angels, the story follows Laharl, the son of a demon overlord, who upon being awakened after a two-year slumber, aspires to succeed his father's place while also fighting rival demons in the process.

Nippon Ichi has also licensed or produced a wide variety of Disgaea merchandise, including a manga. In 2006, Nippon Ichi released a sequel called Disgaea 2: Cursed Memories for the PlayStation 2, as well as a 12-episode anime adaptation titled Makai Senki Disgaea. A PlayStation Portable version of Disgaea: Hour of Darkness was released entitled Disgaea: Afternoon of Darkness, as was a Windows port titled Disgaea PC. A HD remake, Disgaea 1 Complete, was released for Nintendo Switch and PlayStation 4 and later for iOS and Android.

In 2004, the game received a spiritual sequel, Phantom Brave. Disgaea D2: A Brighter Darkness was released for PlayStation 3 in 2013, and stars the main cast (and additional new characters) of Hour of Darkness.

Gameplay Disgaea is a tactical role playing game. Battle gameplay takes place on a map divided into a square grid. The player controls a squad of humanoid units and monsters, which each occupy a single square of the grid and do combat with a group of enemies. Depending on the character and attack selected, the player will be able to deal damage to a specific enemy unit or a designated region of the map. Combat ends when all enemy units or all of the player's units are destroyed.

Humanoid characters may lift and throw other units across the map in order to allow allies to move further or force enemies to keep their distance. This even allows the player to capture enemies by throwing them into the base panel; these enemies then become allies, and can be used on subsequent maps. The chance of capturing an enemy in this manner depends on several factors. Failure to capture the enemy will result in the death of all characters inside the base panel, and the enemy will survive.

Geo Panels Some maps in Disgaea contain Geo Panels, which are represented as squares on the floor of the map of a particular color. Colored objects on the map known as Geo Symbols may be present on either Geo Panels or regular, uncolored squares on the map. These Geo Symbols can usually be thrown. When a Geo Symbol sits on a Geo Panel, it gives all Geo Panels of the color it sits on a property, such as making all units on them invulnerable, or decreasing the HP of friendly units on those panels by 20% at the end of each turn. When a Geo Symbol is destroyed on a Geo Panel of a different color than its own, it causes panels of that color to change to the color of the Geo Symbol and damages units on those panels. If another Geo Symbol is on one of the panels when it changes, it too is destroyed, and the Geo Panels begin to change color and properties again, creating a chain reaction. This chain reaction can be of any length that can be supported by the number of colors of panel and symbols on the map, the amount of "chain" gained with each square increasing by one every Geo Symbol. The higher the chain, the more the bonus gauge fills. Some Geo Symbols have the color "clear" and cause the Geo Panels to become regular map squares when destroyed. Removing all of the Geo Panels from a map will cause a blast of energy which hurts all enemies on the map and results in large bonuses for the player, referred to in the manual as the Panel Termination Bonus.

Laharl's castle Laharl's castle acts as a hub, allowing the player to access the other locations in the game without physically having to travel between the castle and a desired map. Each episode of the game gives the player access to a new set of maps, which must be completed in order to proceed in the plot. With the exception of the Item World and the Dark Assembly, all maps are accessed by speaking to a dimensional gatekeeper. With few exceptions, maps can be accessed and played again at any time, occasionally with minor changes, such as boss levels, where the boss will be replaced by a high level generic enemy.

Disgaea has only one pair of stores where items may be purchased, consisting of an armor shop and a weapon shop within Laharl's castle. These shops are described in-game as the Netherworld branch of the Rosen Queen Co. The overall quality and types of the items sold in these shops can be changed through proposals to the Dark Assembly. A hospital where characters may be healed in exchange for payment is also present in the same area of the castle and rewards Laharl and company by giving them items when they pay specific amounts of money for treatment.

Dark Assembly In order to perform specific actions outside of combat the player must address the Dark Assembly. To create new characters, improve the inventory of the castle store, or unlock new maps Laharl or other members of his party must present a proposal to the Dark Assembly, who will vote on whether they should or should not provide aid to Laharl's party. Prior to voting, senators in the assembly represent their predilection toward the party visually, glowing blue if they favor that character or red if they do not. If they are glowing red, senators can be bribed with items from the player's inventory to sway their vote in the player's favor. If a proposal fails to receive sufficient votes, the player may attempt to pass the bill anyway by choosing to "persuade by force" and attempting to defeat opposing senators in battle.

The proposals available to place before the senate depend on the number of promotion examinations completed by a character; these examinations consist of a battle between a handful of monsters and a single character on the floor of the Assembly. Each proposal to the Dark Assembly costs "mana", which is built over time by individual characters as they defeat enemies in combat. The amount of mana gained depends on the enemy's level.

Item World Laharl's party may also enter the Item World from the castle, going inside an item in their inventory in order to increase its attributes. The world associated with an item contains up to 100 randomly generated levels. Inside the Item World, monsters called Specialists raise the statistics of the item they are in when defeated. Often, the maps are full of Geo Symbols.

Each floor has a gate, a special map square that can be used to go to the next level in the Item World. However, a monster with the unique class "Gate Keeper" will sometimes block the gate. The Gate Keeper must be defeated or forced to move to use the gate and progress through the Item World. Defeating every monster on the map can also allow the player to progress.

Every ten levels has an item boss. The strongest of each type of weapon and the three ultimate items each contain an Item God 2. Defeating these bosses also increases the attributes of the item. The Item World can only be exited at the end of every tenth level containing an Item Boss, or at any other time by using an item called 'Mr. Gency's Exit', a play on the phrase "Emergency Exit". Since many items contain stronger monsters than are ever found outside the Item World, the Item World is often the only way to acquire rare and powerful weapons.

Plot The story of Disgaea opens with Laharl rising out of an open coffin in his room. Etna, one of the castle vassals, is standing next to him, surrounded by various weapons. She explains that he has been sleeping for two years, far longer than he intended, and his father, King Krichevskoy, has died. Laharl vows to reclaim the throne, and, after consulting with Etna and his other vassals, goes to Vyers' castle.

After defeating the demon Vyers, who refers to himself as the "Dark Adonis" and is renamed "Mid-Boss" by Laharl, he meets Angel Trainee Flonne. Flonne had been sent to the Netherworld by Seraph Lamington, the ruler of Celestia, to assassinate King Krichevskoy (who was already dead). Shocked by Laharl's lack of grief at his father's death, the eternally optimistic Flonne joins Laharl's party to determine if demons are capable of feeling love. Observing them in secret is the paranoid Archangel Vulcanus, who interprets Flonne's actions as treason and is convinced that she is plotting against him.

After Etna demands that Laharl pay the salary of the Prinnies that she has hired, he decides to attack the demon with the most money in the vicinity. This is Hoggmeiser at Dinero Palace. After defeating Hoggmeiser, Laharl is about to kill him, until Hoggmeiser's son rushes out and gets in the way. Flonne convinces Laharl to spare them, and Laharl lets them keep some of the money. In response to this act, Hoggmeiser joins the party.

At one point, Flonne and Etna discover a photograph of Laharl in an embarrassing situation. Laharl refers to this as a "paparazzi shot", however, the actual contents of the photo are never actually revealed. A threat on the back of the photograph states that copies of it would be distributed if Laharl did not accept a challenge to fight for the overlordship; thus Laharl was blackmailed.

Responding to this challenge, Laharl meets Maderas, a vampire. He was banished by King Krichevskoy, for stealing the King's favorite snack, black pretzels. Maderas takes advantage of Laharl's two biggest weaknesses – optimism and women with sexy bodies. Maderas was also controlling Etna by holding her memory. He had instructed her to kill the prince, but she had put him to sleep for two years by poisoning him instead. Etna eventually betrays Maderas, and along with Laharl, Flonne, and Mid-Boss, defeats him.

Waking up later at night, Flonne discovers that several Prinnies are chanting and leaving the castle. Laharl, worried that his reputation will be tarnished if it is discovered that he let his vassals escape, chases after them the next morning. Eventually, he runs into Death, and the player learns that Big Sis Prinny is actually Laharl's mother; she became a Prinny because she gave her life to save him.

After Laharl becomes the undisputed Overlord of the Netherworld, he meets a group of humans from Earth: Gordon, Defender of Earth; Jennifer, his assistant; and the robot Thursday. Gordon has been led to believe that his mission is to assassinate Laharl due to an impending attack on Earth by the Netherworld. Laharl promises not to invade Earth if Gordon defeats him, on the condition that Gordon becomes one of his vassals if he wins; Gordon is embarrassed by his ensuing loss and servitude. After the Earth Defense Force appears in the Netherworld, it is revealed that Gordon was actually sent to secure a path for an invasion of the Netherworld by the humans, who had been tricked by Vulcanus.

General Carter sends Kurtis to the Netherworld, and eventually goes there himself on the Space Battleship Gargantua. Kurtis abducts Jennifer, and Laharl engages the EDF fleet of spaceships in a rescue attempt, destroying all but the Gargantua by himself. When Laharl and his party arrive at the Gargantua's bridge, several angels from Celestia appear and attack them. After being defeated, General Carter escapes, only to have Mid-Boss appear to give him a message.