amanogawa shiina (1st costume)
The default costume of Phase Connect's Amanogawa Shiina, as seen in post #5498937 and post #6018403.
It consists of a white dress with a purple bowtie and see-through middle, detached sleeves decorated with black ribbons, black panties, and white, knee-high boots.
This tag implicates amanogawa_shiina (learn more).