Yeonhwa

The ancient Ritual Instrument, the Kasuibon, itself. Or perhaps an artificial soul manufactured by it.
Considering that, it has a well-formed personality and set of emotions. It's still impossible to grasp exactly what exactly she's feeling at any given time.
She is always smiling softly in an aloof manner, but she occasionally gives off a chillingly serious demeanor.

Her ears are really big and often waggle. Her tail is fluffy and often gets its hairs tangled. Once properly groomed, it becomes a wonderful tail.
It's not clear what it originally looked like as a Ritual Instrument. It might have been vase-shaped, but there's a chance that it could have had a totally different form.
She said, "I can't see Ryufa in my current state," but she frequently tries to get me to talk to Ryufa.