The default costume of hololive's Amane Kanata.
It consists of a grey cropped jacket with long, wide sleeves going with sleeve cuffs past her wrists with aiguillettes and a white sailor collar, worn over a white shirt and a black turtleneck dress (although it's often depicted as just a separate turtleneck shirt and black frilled miniskirt), a blue bowtie, a yellow armband, blue gingham kneehighs held up with legwear garters and black boots.
This tag implicates amane_kanata (learn more).