As usual, the lineage of even one Disgaea game, or NIS SRPG to be less specific, can get complicated.
The original Disgaea 5, which told the tale of Killia and his revenge against the Demon Emperor Void Dark, was released in 2015 on PS4. Then it pivoted onto Switch on 2017, and this year, Steam. The latter two are actually billed as "Complete" editions, which include all sorts of previously released DLC and gameplay tweaks.
We've known about the Steam version for a bit, but as of this week NIS gave us a final release date -- May 7, 2018. If you don't own a Switch it's probably worth picking up, but just make sure the PC port is A-OK first (given that Disgaea's Steam port was a success, it probably will be, but you never know).
Disgaea 5 Complete [Steam]
via destructoid https://www.destructoid.com/disgaea-5-complete-dated-on-steam-498265.phtml