La Pucelle wasn't released in the U.S. until May 2004, over half a year after the game's pseudo-sequel Disgaea: Hour of Darkness (2003).
The main character, Prier, is actually a hidden character in Disgaea (though the name was misinterpreted as "Priere"). Complete the area "Alternate Netherworld" to recruit her, but make sure that you have passed the proposal at the Dark Congress to open the portal to that area (and be at the final episode, of course).