Originally Posted by stgermain
Each game is a standalone game, though you won't get certain references, especially the post-game bosses which involve characters from previous Disgaeas. Do be aware that if you start with this one, it might be harder to go back to the previous ones, since each game adds more and more features. If you like strategy games like the ones that you've mentioned, you should check this series out. You'll become addicted leveling characters to 9999 and making powerful weapons. The first two games can be found on the PS2 and PSP, and the third and fourth games on only on the PS3, though the third one will get ported to the Vita.
Disgaea 1 is also on the Nintendo DS, but I think the PS2 and PSP versions are better.
Well the Disgaea games do have some connection to eachother, but not enough to make you think you have to play the 1st game to understand the story. While there is the connection, but with a different main cast of characters in each game with some cameo appearances of characters from previous Disgaea games as well as other characters from other Nippon Ichi Software titles, you should be fine to start off with this game.
Gameplay-wise though, it would probably be better to start with the 1st game.