What If ...?
As mentioned in the walkthrough, there are nine endings in Disgaea D2. The “true” ending is the one you receive by facing and defeating Xenolith’s final form, and is the only one that unlocks the Post-Game content. The other eight are non-canon in obvious and spectacular ways.
After you receive an alternate ending, you end up back at Episode 1 after the credits just as if you’d started a new cycle. Your levels, money, equipment, roster, and other changes all persist into this new game, but as far as the story goes, you’re back at square one. If you’d like to prevent this, you can simply reload your last save, but doing so does not save the ending in Memoria or Paparazzi’s archive of events.
The alternate endings can be unlocked as follows:
Overlord Sicily
Get a game over when fighting Sicily in Silver Witch.
The Fall of Overlord Laharl
Get a game over when fighting Barbara in Inner Sanctum.
Girl Laharl Forever
Get a game over when fighting Hoggmeiser in Green Room.
Netherworld Collapse (Lose)
Have 20 or more ally kills among your characters and lose the fight against Barbara in Utopian Abyss.
Netherworld Collapse (Time Over)
Fail to defeat all of Barbara’s forces before time runs out on Utopian Abyss.
Pure Flonne the Awakened Angel
Three or more characters must have reached a five-heart Likability rating with Flonne. Get a game over on Netherworld Maw.
Etna’s Magic Overload
Three or more characters must have reached a zero-heart Likability rating with Etna by the time you’ve cleared the first half of Netherworld’s Guts. After you beat Xenolith, a dialogue choice will spring up. Choose “Yes.”
Note that this is the only alternate ending that you can see by winning a fight.
Sicily’s Sacrifice
Get a game over on the second half of Netherworld’s Guts.