This is a list of the various endings and their requirements in Disgaea 3: Absence of Justice.
Main Story Endings[]
Normal Ending[]
Don't meet any other ending's requirements.

Disgaea 3 - Normal Ending Credits
Super Hero Aurum is defeated and backs down. He explains to the party the whole reason behind his actions, ending in him asking to be killed by Mao and released from his tormented life. Mao refuses to have a "normal" ending like that and decides to keep Aurum as a "guinea pig for his experiments." Once sent away, Mao heads for his Dad to kill him, break the spell holding him to the world, and let him pass on to rest in peace. When they arrive however they find his soul is already passing on. It turns out Mao's Dad was just worried about Mao. He speaks to him and confirms his relief that Mao had grown into a strong, mature individual. He declares Mao the new Overlord and leaves the Academy in his hands. Post credits, Almaz speaks off screen about the events following the finale: Salvatore the Magnificent came to challenge Mao to a duel, it ended in a draw, Master Big Star tried to render a decision, but they both insisted that they won and were quite upset with the results, Mr. Champloo cooked a feast so large, no one could finish it, then disappeared before anyone noticed, Super Hero Aurum was taken prisoner in Mao's room, as dictated, and Almaz left the Netherworld with Sapphire to get married.
Super Hero Ending[]
Defeat the final boss using Mao at Level 500 or higher.
Super Hero Aurum encourages Mao to deal the killing blow and end his life, to which Mao refuses, claiming his hatred for Aurum has disappeared. Mao's Dad begins to speak, commenting on how Mao has matured. He tells Mao that Super Hero Aurum is already dead. He will be reborn as just regular Aurum. Mao's Dad informs Mao he is the new Overlord, passing on happily with no regrets. It appears Mao's Dad couldn't pass on prior to now because he was worried about Mao's growth as a person. Aurum is left disgusted at the idea of being reborn with Mao and his party until Raspberyl and Almaz make him realise he can change his opinion on Demons. Mao eventually admits that having an evil, and skilled butler would help him become a greater Overlord than his Dad was, causing Aurum to agree to become Geoffrey once again. The game ends with Mao at his castle asking Geoffrey for his first task as Overlord. To which Geoffrey happily obliges.
Almaz's Ending[]

Disgaea 3 - Almaz Ending Credits
Beat the final stage 8-4 with only Almaz and win the ensuing battle.
In this ending Mao is desperate to deal a final blow and kill Super Hero Aurum for good. Almaz and the rest of the party acknowledge they've won and attempt to convince Mao to stop, not wanting to see his heart in pain anymore. Mao gets angry and declares he will drop everyone for standing in his way, a message then appears stating he has dropped out of the group. The rest of the party, shocked, decide they must use brute force if Mao refuses to listen. Almaz steps in and with the intent of bringing Mao to his senses, he forces Mao to duel him one-on-one claiming: "a hero must stand, face forward, against it!" The player must then fight Mao using only Almaz and win. At which point Mao's Dad thanks Almaz for disciplining his son on his behalf. He remarks on Almaz being a "dependable guy" and declares him the new Overlord. Mr. Champloo congratulates Almaz, however Mao, Raspberyl, and even Princess Sapphire instead declare how now Almaz is an Overlord they will return to kill him. The credits then roll with a distressed looking Almaz in the background.
Human World Ending ("Bad Ending")[]
Before you reach stage 7-6 kill more than 99 allies and clear 2 alternate stages.
Mao, upon finding the portal to the human world (Super Hero Aurum's home), declares he will kill all humans. The guardian of Mao's heart appears before everyone and attempts to stop Mao from giving into anger and hatred. Mao's party, fearing for the fate of the Human World also try and calm Mao down which only angers him further and causes him to turn on his heart's guardian. Once the guardian is defeated, it warns the rest of Mao's party to try to escape but is interrupted as Almaz succumbs to his curse and dies. Mao shows no remorse at Almaz's death and proceeds to the Human world alone. Once there, Mao begins to "destroy" the Human world until Raspberyl appears and attempts to stop him with the help of Princess Sapphire, Kyoko Needleworker, and Asuka Cranekick. Once confronted, Mao claims his only crimes are replacing stop signs with yields, hiding people shoes, and prank calling places. Unfortunately however, the four do not believe him and choose to fight. Once Mao defeats them Super Hero Aurum appears, eager to fight Mao as he is now a powerful Overlord. Mao begins to harness his 'true power' causing Raspberyl to attempt to stop him and be killed by Aurum. No one is present to stop Mao as he unleashes his full power and kills Aurum. Mao is left seething with power as the screen cuts away and Mr. Champloo comments that no one can stop Mao now. The Credits roll and the background displays Mao surrounded by fire. Once the credits finish rolling a voice reads aloud: "And then there was no one." "No Human world, No Netherworld, No Celestia, Everything disappeared and was gone..."
Extra Endings[]
Mao's Ambition Ending[]
Before reaching stage 4-4, clear stage 1-9 on 2nd or higher cycle.
Mao can't believe he beat his father with his own hands. Almaz is similarly impressed with himself but is told by Mao that it was all down to him. Mao's Dad proclaims that he still does not possess "some things" but doubts himself asking "is that... okay?" Mao wishes to know what he missed, but his Dad passes on without another word. As the events of the game never unfold in this ending, Mao remains with the Hero title and Almaz becomes a Demon. One year later Almaz is seen attempting to mug the Vato Brothers in an overly polite and apologetic manner as he needs money to survive. They mock him and threaten to show him how to properly mug someone, but are stopped by Mao who apparently now has a reputation as a Hero with a "worse nature than any hero in any game!" Mao demands payment for saving Almaz. Almaz gets upset and angry at how everything has turned out for him. He tells Mao this never would have happened if he returned the title, to which Mao explains he tried to give it back but it wouldn't come off. Regardless, Mao is happy with how his new Hero lifestyle has turned out. The two of them conclude the only thing left to do now that things have played out this way is to reset the game.
Raspberyl's Ending[]
Lose against Raspberyl on stage 1-5 or 2-1.
Raspberyl achieves her dream of becoming the greatest delinquent. Many accomplishments become attributed to her name, including negotiating a peace between two warring overlords, and creating a device that generates power from friendship. In a closing narration, it is revealed that she passed away peacefully in her sleep at the age of 10,108. Her list of achievements are given afterward, and include having 5,097,149 demon friends and 666 human friends.
Laharl's Ending[]
Go to Homeroom and propose 'Watch a New Ending' and clear the final stage 8-4.
Laharl suddenly appears before Mao alongside Etna and Flonne, claiming to be Mao's father. Mao doesn't believe him at all and a battle ensues. After defeating him, Mao begins to call Laharl his old man despite being skeptical earlier. However, it turns out that this was all an attempt to steal the lead role and he reveals to Mao that he is actually another Overlord after the battle. Flonne, attempting to avoid negative repercussions insists that she is still Mao's mother, only to have Etna criticize her behavior, remarking she can't believe Flonne was once an Angel (Flonne). The credits roll shortly after with a picture of Laharl, Etna, and Flonne in the background.