Loose socks Wikipedia
Loose socks (ルーズソックス, rūzu sokkusu) are a style of baggy sock worn by Japanese high school girls, as part of kogal culture. This style of socks has also become popular among American teens and college students who are fans of Japanese anime and manga. These socks come in a variety of styles—defined by the knitting pattern of the upper. The two most popular styles are the traditional 2×2 rib knit (pictured) and tube-style loose socks, which are thigh-high length tube socks worn pushed down around the ankles.
They were adopted as a fashion which flattered plump calves and also expressed rebellious deviation from Japan's strict dress code for school uniforms. It is used as an inspiration for photography by Akira Gomi. They are also used in Japanese fashions like Kogal and Fairy Kei.