loose socks
Created by juunigatsu no usagi.
Wikipedia on Loose socks
Socks with leg volume, worn (usually) bunched below the knee and mainly come in white. In Japan, they were adopted as a fashion among high school girls, gradually deviating from being worn with school uniforms and firmly taking root after a long period of popularity.
They originated from boot socks for mountain climbing, manufactured in and exported from the United States.
They look like legwarmers, but legwarmers are tighter above the knee, and are footless.