A new project related to Ninja Gaiden seems to be in the works, going off of an announcement from the series’ composer Keiji Yamagishi. Here’s Yamagishi’s recent statement from Twitter:
“I’m pleased to announce that I’m working on a new project related to Ninja Gaiden. I’ll be able to share more news in July!”
Whether this new project is an actual game or something simply related to Ninja Gaiden, we’ll have to wait until July as Yamagishi said to find out.
Update: Yamagishi-san updated on Twitter saying that the new project does not relate to a new video game.