A new ordinance to regulate dating services pairing up men with teenage schoolgirls came into force Saturday in Tokyo.

The Tokyo Metropolitan Assembly unanimously passed the ordinance Friday that prohibits girls 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," meaning female high school students.

JK business operators are now obliged to file a business registration with the Tokyo Metropolitan Public Safety Commission and make a list of employees to verify their ages. Police officers are also entitled to conduct an on-site inspection under the ordinance.

Violators face penalties of up to one year in prison or a fine of up to 1 million yen ($8,900).

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

Earlier this week, the U.S. State Department issued the 2017 Trafficking in Persons Reports, and Japan was graded Tier 2, the second rank on a four-level scale, for failing to "fully meet the minimum standards for the elimination of trafficking."

The reports said variants of JK Business continue to facilitate the sex trafficking of children.