Extra Classes
Note that just having the mastery isnt enough you'll then have to petition the Dark Assembly with the appropriate bill to be able to create them. Unlockable How to Unlock
Archer Have someone with a level 5 bow mastery
Male Ninja Have someone with a level 5 fist and sword mastery
Female Ninja Have someone with a level 5 fist and staff mastery
Samurai Have someone with a level 5 sword mastery
Gunner Have someone with a level 5 gun mastery
Chaos Soldier Finish the game once
Heavy Knight Have someone with a level 3 spear mastery
Magic Knight Have someone with a level 3 sword and staff mastery
Beast Tamer Successfully capture a monster
Sinner Someone in your party becomes a criminal
Wiseman Destroy 500+ Geo Panels
Star Mage Level Ice, Fire, and Wind Mages to level 25

Alternative Endings.
Here is how to unlock the different endings. Unlockable How to Unlock
Etna Ending Defeat Etna in Chapter 3
Laharl Ending Defeat Laharl in Chapter 11
Middle Boss Ending Defeat Mid-Boss Before Chapter 4
Tink Ending Defeat Final Boss with Lvl. 1000 Tink
Akutare Ending Get Defeated by Akutare
Bad Ending Have Adel 10+ Previous Offense, Killed Ally 50+ Times, Then Finish The Game
Worst Ending Have Adel 99+ Previous Offense, Killed Ally 99+ Times, and Rossary Formarly Dead
Proposal Ending #1 Once you've passed the proposal, "See the ending!", beat Extra Stage 5
Axel's Endings Be defeated by Axel in Stages 1-4, 2-4, 4-4, or 7-4
Felony Ending #2 Adell must have 99 Felonies, and you must have 100 or more Ally Murders, including Rozalin
Felony Ending #1 Adell must have 10 or more Felonies, and you've committed 50+ Ally Murders
Proposal Ending 2 Pass the proposal, "Pick a fight with an Overlord!" Clear the extra stage.

Unlocking Flonne and Laharl. Unlockable How to Unlock
Laharl After getting Flonne, have Adell become a senator. Attend Dark Assembly and pass Flonne's "Summon Laharl!!" proposal. Beat Extra stage 9.
Flonne Play 40 hours to unlock "I want to fight an Overlord!" proposal. Pass it to unlock Extra stage 8 "In Holt Village" Beat it and she'll join you.

Unlock Friday MKII/ Dark Guide
This NPC is the dimension guide in which you can play the "dark" version of stages you have already gotten up to. These dark stages are challenging and much harder than the actual stage they are supposed to represent (the first stage has 3 lvl80 monsters). To unlock her you must press 5 buttons hidden throughout the town. These buttons are invisible and you must press X when you are near them to "press" them. The first button is located behind the knocked-down square column behind the Post Officer. The second is located behind Adell's house against the wall in the corner. The third is located on the very bottom right hand corner off the map where there is a patch of grass next to a tree. The fourth is located in a break in the wall of the left leg of the cross where the Petite Orc is standing in the middle. The last button is located behind the house located just left of the previous button. It will be against the wall. After pressing all buttons it should say "An eerie shadow lurks upon Holt Village". After doing this Friday MKII will appear under the tree located near the third button. Make sure to save before fighting her because if you are a low enough level and you lose it will results in a game over and you will lose all unsaved data previous to the fight. Unlockable How to Unlock
Friday MKII/ Dark Guide Defeat her in a match. She will now be a usable NPC dimension guide.