JSK stands for "Japanese School Uniform." It is a type of school uniform that is commonly worn in Japan. This tag is used to describe porn videos featuring individuals wearing Japanese school uniforms as part of their attire during the scenes. These uniforms typically consist of a blouse, pleated skirt, knee-high socks or stockings, and sometimes a tie or jacket. The JSK tag indicates that the content may contain roleplaying scenarios set in a school environment, or simply feature individuals dressed in this specific type of clothing