Overlord Zenon has cursed the people of Veldime to turn into monsters, slowly losing their memories and morals. Adell's mother is tired of living as a monster and wants to return to being a human. She is a powerful summoner and casts a spell to summon Overlord Zenon so that her son, Adell, the only human left, can defeat him and break the curse. However, instead of summoning Overlord Zenon, her spell summons his only daughter, Rozalin. Adell must now return her to her home and complete his original quest: find and defeat Zenon.
The game is set up in 2-D, with the protagonist, Adell, always being the person you have to play as when you are not out fighting demons.
To use the Dark Assembly you must approach the Dark Secretary in Veldime and request to enter the Dark Assembly. The system is quite easy: choose which character you wish to create a bill with, choose which bill you want to bring to hand, (e.g. More expensive items, Greater Counter, I want to fight an Overlord) but you need to have enough Mana to do it.
When you have enough Mana to do that bill it is spent if you wish to bring it to hand. When you begin your proposition there will be Senator demons agreeing or opposing you. To change the red to blue (or the blue to bluer), bribe them! Then press triangle and begin the vote. The Senators will began voting "Nay" or "Aye". If there is enough influence on the "Aye" side, the bill is passed, otherwise it fails, and you can choose to try to pass the bill by force.
You can also create new characters by using Mana. You can choose a number of different "grades" (e.g. Good-for-nothing, incompetent), and better grades cost more Mana but give you more bonus points to add to the new character's stats.
In the game fighting is just like walking in Veldime, but the field is set up like a board game. Select move and then click the tinted square you want to move to that area. If there is an enemy beside you press attack or skill and select that enemy. Some skills take up a large amount of space. If you want to do that move and continue to set up your characters then press execute. When you have everything as you want it press Triangle and then select end turn. In short, a lot like Disgaea: Hour of Darkness.