When you hear the expression "JK business," do you have any idea what kind of work this refers to? JK stands for joshi kōsei (high school girls). In Japan, JK is a very powerful brand — and high school girls are a highly valued commodity.
In the 1990s girls sold their worn and unwashed school uniforms, gym shorts and bathing suits for a pretty yen at so-called buru-sera shops. ("Burusera" is a portmanteau of "bloomer," which in Japan means the type of high-cut sports shorts still worn by volleyball players, plus "sailor suit" — the girls' school uniform that has become the garment of choice for costume fetishists.)
Later came enjo kōsai, or "compensated dating," which entailed high school girls selling themselves, in one way or another, to middle-aged men. Every time Japan tries to squash one form of exploitation of high school girls, another type raises its ugly head, like some sort of desperate game of whack-a-mole.