[@rocketrobie2][@GingerBoi123]

Glad to have you!  

So, on magic and science. 

As I said, I don't want to restrict this too much as far as what is possible. Mainly I just want to make sure everything is cohesive. 

For tech, think of this as a near future sci-fi. The Marvel movies would be a good place to look when thinking about what is possible. 

This is a world where people can have extraordinary abilities. You can be born with powers, or you can acquire them from the Oni. 

An Oni can "bless" someone, and give them powers. This leaves a physical mark on the bearer, and can be taken away at the whim of the granting Oni. Obviously, this is the kind used by people who work for or with the Oni, and most citizens hate anyone with an Oni mark. 

Power can be taken from an Oni too, however. An Oni's mask can grant a human powers, even without the Oni's consent. Taking an Oni's mask is both difficult and dangerous. It won't come off except with great force, and only if the Oni is too weak to resist. 

Mask bearers have a certain level of prestige among Ronin.

Extra notes on Oni, too: 

Oni cannot die. Conversely, however, they also don't heal the way humans do. Or possibly at all, it's not clear to human observers. 

Oni will patch themselves up when possible, even to the point of sewing their own head back on. If they are too damaged to continue living among and terrorizing humanity, they will retreat to their Hell of origin, and usually aren't seen again within any human's lifetime. It is known, however, that Oni can and do return, thanks to comprehensive records taken over the centuries. 

An Oni who loses their mask will rampage until rendered unable to move. It is other Oni who dispose of them, taking them from humans by agreement or by force. It is generally supposed that they are sent back to one of the halls.