A new ordinance to regulate dating services that hire teenagers took effect Saturday following its unanimous passage by the Tokyo Metropolitan Assembly the previous day.

The ordinance prohibits people younger than 18 from working for such operations.

According to the Metropolitan Police Department, this is the first ordinance in Japan specifically targeting the so-called JK business. JK stands for joshi kosei (female high school students).

Violators can face penalties of up to a year in prison or a ¥1 million fine.

In Tokyo, police have confirmed there are 110 JK business establishments and 30 related businesses without any office or facility. Some of these establishments have been known to covertly provide sexual services.

Last week, the U.S. State Department issued the 2017 Trafficking in Persons Reports, and Japan was graded Tier 2 on its four-tier scale, for failing to "fully meet the minimum standards for the elimination of trafficking."

The reports said variants of the business continue to facilitate the trafficking of children for sex.