During yesterday's Nintendo Direct, NIS America announced that Disgaea 5 Complete will be getting a playable demo. Unfortunately, no details on the release date and content of the demo were provided.
Originally released for PS4, Disgaea 5 Complete comes with all post-launch content released for the PS4 version. This includes all 8 bonus scenarios, 4 fan-favorite characters, and 3 character classes.
Disgaea 5 Complete releases on the 23rd of May in North America and on the 26th of May in Europe.