We could really use a prequel in the Oni storyline.
The game would involve the Oni War. In Oni 1 we saw stories and pictures of past Oni warriors. It could also shed some light on the Oni, the Genma, and Marcellus’s character.
From Oni BW we know that Marcellus was involved in the Oni Wars. We would of course play him throughout the game. Now a bonus to the game, or maybe a second disk, would be beating the game like once or two times would be that we get play a younger Samanosuke before he became an Oni warrior. That story would be set where he and Kaede first met. I mean since Samanosuke is the main character of the Oni games we should know more about his past.