Siliconera: "Also it looks like Disgaea 2 Portable, well at least this version of it, may not have any multiplayer features. A quick glance on the Japanese page says the game only supports one player.
You may not be aware of this, but there are actually two versions of Disgaea: Afternoon of Darkness in Japan. Originally, the Disgaea PSP port did not have a multiplayer feature. A year later Nippon Ichi re-released it with multiplayer as budget version of Disgaea Portable. NIS America spared us this fate and just released the multiplayer ready version of Disgaea: Afternoon of Darkness. This delayed the domestic release about a year, but at least we didn't have to buy the game twice. Perhaps, the same thing will happen with Disgaea 2 Portable?