The default costume of hololive English's Nanashi Mumei, as seen in post #7368879.
It consists of a cloak and capelet secured by a ribbon and a longer cape that splits like the feathers of a wing, a white buttoned shirt with a cleavage cutout, brown corset, gloves that are fingerless on her index and pinky fingers, waist belt with a lantern, pouch, and small dagger hanging from it, red pleated miniskirt, asymmetrical legwear (single thighhigh on left, single kneehigh on right), and brown ankle boots.
Her main hairstyle here is long hair in a ponytail, held in place with a feather hair tie. Her bangs are secured by a rune-shaped hairclip.
This tag implicates nanashi_mumei (learn more).