A new ordinance comes into force in the Japanese capital tomorrow targeting a murky corner of the city’s nightlife. The JK industry is the innocuous-sounding name for dating services with teenage girls. Businesses sell time with the girls to male clients (JK stands for joshi kosei, or “female high-school student”). Campaigners say the industry is a portal for child prostitution and that men use the private settings provided by the businesses to press girls into having sex. Police reckon that about half of the girls who work in the business end up sleeping with customers. A UN expert has criticised what she called “institutional” tolerance of businesses that sexually exploit kids. Police have raided JK companies, which have responded by offering harder-to-detect options, even “fortune telling”. The ordinance bans under-18s from working in the industry and introduces fines of up to ¥1m ($8,880) for violators. It lists five specific services as illicit, including massages and “sleeping side by side”.