Ill answer the question with another question,
Do Ryori's Eat?

But in all seriousness, do they? Are the pictures we see of them on Sylestia taken at just an angle that we can't see their mouths? Do they eat some other food such as energy that they just absorb through their skin instead of eating? Do those orbs around their heads have mouths we don't see? Do those orbs just make energy for them? Maybe they use an advanced form of photosynthesis? I have no clue, these are just some interesting ideas I made up on the spot.

Okay; this may be a bit of a stretch, but what if they use a process sort of like chemosynthesis? Pretty much their cellular structure is different than a normal animal or sylesti, as they have traits no other one has (the pale eyes, living in the spirit realm, and the ghastly ring, and mainly lack of mouth) When dead bodies start to decay, they release many toxic chemicals. I dont think it would be that large of a jump to say that souls do the same. Perhaps these chemicals are food to the Ryori, and the spectral rings are either the byproducts or the chemosynthesis being released, or a way to absorb it like a plant leaves.



Or maybe they just eat through their butts. The sky is the limit

I like to think that they absorb energy. Saying they absorb it through their orbs sounds nice.
Or you know...they don't eat at all.

But then Why am I paying to feed it!

My best suggestion would be that perhaps they don't? At least not physical food anyway. That food charge for them on the stables? Probably another Sylesti growing extra fat by eating their share of the foods.

What if the Ryori's ARE food

No.