Today, during the APM D-1 Fighting Festival tournament organized in Tokyo by Sega, Dead or Alive Producer Yosuke Hayashi appeared during the segment dedicated to the arcade version of Dead or Alive 5: Ultimate.
At the end of the competition, Hayashi-san introduced new content coming soon in Dead or Alive 5: Last Round.
First of all, he showcased the Tatsunoko Mashup costume set coming in Jnanuary, including costumes from classics like Yatterman and from Nurse Witch Komugi-chan R.
Secondly, he showcased a video, that you can see below. The video is related to content appearing in March (and a little earlier on the arcade version, according to Hayashi-san), which points to the new character that was mentioned, but never revealed in months past.
The mention of a collaboration with the Samurai Warriors series and the outfit, are pretty much unmistakable. It's Naotora Ii from Koei Tecmo's hack and slash series.