The following endings are unlocked when the indicated options have been selected during the game.

Unlock Good Ending:
Without killing allies beat the game.

Unlock Bad Ending:
On the 100th floor of a 'Legendary Item' defeat the Item God.

Unlock Dark Assembly Ending:
In the Dark Assembly persuade by Force 100 times.

Unlock Flonne Tradegy Ending:
Kill at least 50 allies before Episode 3 and the Lavish Hall battle and then select to Kill Hoggmeiser.

Unlock Etna Heroine Ending:
Kill at least 100 allies before Episode 5's Ice Queen Battle and then select to kill Maderas.

Unlock Overthrow Earth Ending:
Clear Human World.

To unlock this mode without going through the game enter Triangle, Square, X, Triangle Square, X, Circle at the Title screen. If the code has been entered correctly you will hear Etna's voice as confirmation.