Recently, I have been playing a lot of Nioh 2. And it has me thinking about starting up a new L5R game in the near future.
However, I was thinking it might be fun to upset the entire dynamic a little bit and add some of Nioh to it.

My short campaign idea is this: The Kaiu wall has fallen.

It has been two years since a terrible Oni gathered forces against the wall and brought it down. Rumors are that the clan was betrayed, by allies or from within, but the truth is not fully known.
The Oni himself was taken down in a heroic sacrifice by the Crab, and the shadowland's army scattered, but deep into the Empire as well as back into the Shadowlands.
Now, yokai, goblins, oni, and the taint have made their way deep into the heart of the Empire.

A new normal has set in.
The Crab clan was disbanded in disgrace.
Fu Leng has not returned, and while the fear existed at first, clans have turned on each other for more 'pressing' matters.
Bandits as well as yokai and oni roam the countryside, and bands of Yokai Hunters have begun to prop up.
Some Daimyo have begun to enlist or bargain with Shadowlands creatures to consolidate power, while others remain staunch in their vigilance against the taint.
The taint itself has become concentrated in pools within the empire - perhaps the old mountain village was overrun by goblins, and the nearby trees weep blood, but down the road, the taint is not pooling and has no hold.

The players will be disgraced crab clan, ronin, mercenaries, and the like - seeking fortunes as Yokai Hunters, but also secretly, or not so secretly, hoping to earn their honor back... and that of the crab.
The inciting moment of the game will be them discovering that the Oni who took down the wall was directed by another, and that person is seeking black scrolls, and that the empire, fractured as it is, is within their hands.

Thoughts, suggestions, pitfalls, or does this just sound too off base?

Sounds cool. It'd be a very different view of the empire!