This is a neat game. I feel as though the basic samurai units might be a little overpowered, though: I plonked down a bunch of Samurai Bells in my first turn (ever) and found that was all it took to gain a huge advantage right off the bat. You don't really need to worry about healing units when you get a new one every couple of turns and ranged attacks offer little advantage unless you've got enough troops that you need to deal damage from behind the front lines (which the Oni army never did). The Samurai might be more balanced if they were mostly good for holding ground without being able to deal serious damage themselves. It might also help if units retaliated when attacked, though I realise that would be a fairly substantial change to the game as a whole.
I think 3hoursonly has a point about the camera movement causing motion sickness, by the way. It wasn't a big issue for me but I'd prefer to be able to click and drag with the middle mouse button to move the map anyway: it's considerably smoother if you want to move the view to a new area altogether.
Still, this was fun without needing any kind of tutorial which I find is a bit of a litmus test for good design. I see it's marked as "on hold" on Itch but I'd be keen to see what you do with it if you ever come back to the project.