So, this isn't super relevant right now because Ryouma is in high denial mode about what he is, so he's not rushing to explore the meat rooms, but I figured I'd ask just to have a solid answer for it going forward since it might have some interesting applications down the road.

How would the acid in the cistern affect someone whose body isn't made of flesh and blood? There is a lore precedent for this sort of thing, which is what got me thinking since if he potentially won't die immediately, maybe something else will happen. I have a lot of fun messing around with the consequences of world effects on the magic body, so I will probably have questions like this a lot SORRY!

Of course, cistern!acid doesn't have to work the same way canon!acid does, and in fact, if this is an opportunity for you to do something extra horrible or spooky with this, I am here for it! And if the answer is just "yeah, he'll dissolve too", that's also fine! Basically, immunity is lame, so how do we make this worse.