The Disgaea series has cumulatively reached 5 million units shipped
The Disgaea series began with the original PS2 title Disgaea: Hour of Darkness in 2003, and the franchise recently reached six numbered mainline entries with the recent release of Disgaea 6: Defiance of Destiny. There have of course also been several re-releases, ports, and a handful of other entries like Disgaea D2. Currently, new DLC is set to come to Disgaea 6 in the coming months.
The press release notes that Disgaea has reached popularity worldwide due to its comical storylines, unique characters, and challenging gameplay elements.
A commemorative artwork can be found below.