The "Unidentified Fantastic Flying Girl".
Extra Stage boss of Touhou's Undefined Fantastic Object and Extra Stage midboss of Ten Desires.
A fearsome youkai defeated by humans several times in the past, but whose true form has never been revealed due to her shapeshifting ability by way of her Seeds of Non-Identification. She goes out after living underground for centuries to cause mischief for Murasa Minamitsu and her crew who are out to save their master Hijiri Byakuren.
Friend of Futatsuiwa Mamizou.
Person: black hair, short hair, red eyes, asymmetrical wings, red wings, blue wings, pointy ears
Outfit: black dress, short dress, short sleeves, frilled dress, tomoe (symbol), center frills, buttons, red bowtie, thighhighs, black legwear, mary janes, red footwear, footwear bow, red bow
Accessories: wristband, trident, holding polearm, snake