miya is rabbit-like. but she is not an actual rabbit. as a demi-spirit, she primarily takes on the race of the non-spirit parent (in this case, human). her default form as a spirit, meanwhile, takes the shape of something close to her true nature. in this case, that's a rabbit-like creature. but there are key differences if you look closely enough.
the most obvious difference are the sounds she makes. rabbits do not go 'kyu' last i checked. they also do not essentially function as a heater.
lastly, they most certainly do not have a set of fully functional, omnivorous teeth. yes, miya is still an omnivore even as a "rabbit." throw her a delicious piece of (cooked) pork belly and see what happens (raw meat will make her sick please don't do this).