I had this idea earlier and want to give it a shot;

In a world where petrolum never became a thing and coal still rule as king of fuels, you are a young girl in Nippon, also known to the outside world as Japan, when a strange new fuel known as Crystaleum was discovered in your country, making the Crystaleum Rush, as it will be called in the future, start right under Tokyo and prompting the country to be torn apart by greed, your parents either dying or selling you off for the addictive new fuel. Devastated and scared, you ended up lucky enough in your misfortune to be taken in by a stuggling okiya (a geisha house) as one of their apprentices, not being aware, as you are still young and naive, that things are not as they appear. Indeed, you are now apprenticed to one of the last remaining ninja clans of the kingdom, comprised only of females, and will now start your life as both an entertainer, a spy, and an assassin.

You goal is to survive, along with your clan, at any cost in this changing world where ancient japanese customs clash with victorian industrialism and the harsh whispers of corruption. This will be hard, you will struggle every step of the way but, perhaps, by doing so, you may find balance. So enter the madness and do not look back.

So people would be playing as members of this ninja clan?

Yes, think of it as an action-packed collective biography as the character starts really young.

I'm curious about this so I'll tag that as interested

Where does the Wild West come into it?

The Rush will attract lots of different people, and things will quickly get rowdy, with prospector fighting for land, countries for ressources and with that outlaws and contraband will flourish in the wasteland that will become Japan. Yakuza will mingle into a cowboy lookalike and okiyas will become half saloon, half tea houses.

I wonder if I should scrap the AU elements as well as the Wild West and keep it in a more or less faithfull rendition of the Meiji era. Thoughts?