A woman in her 30s in Kagawa Prefecture checked a website offering videogame walk-throughs at the request of her child.

But instead of being dazzled by solutions to puzzles or paths through mazes, she was stunned by all the advertisements leading to online adult entertainment comics and games.

Although the ads did not show explicit depictions of genitals or breasts, the mother thought they had no place on the site.

Such sexually suggestive advertisements have proliferated on websites for children due to shifts in technologies and absence of regulations. And there is now a strong push for the government to do something about it.

Last autumn, the Kagawa mother started an online signature-collecting campaign calling for “zoning” on the internet, similar to a corner for X-rated content at bookstores and video rental shops.

The petition on the change.org website has gained about 100,000 supporters.

“Standards are too lax on the internet, compared with television and newspapers,” said the woman, a mother of three children between 2 and 10 years old. “I want to see higher levels of self-regulation.”

Previously, website operators usually signed contracts directly with advertisers and reviewed the ads before they were published.

However, a method known as “programmatic advertising” has become dominant in internet advertising in recent years, and it does not allow pre-vetting.

Under the system, website operators only sell ad spaces and do not conclude contracts with advertisers.

An auction for an ad space is conducted instantaneously every time a viewer visits a website.

The winner’s ad, which is selected based on bidding price, content, viewer properties and other factors, automatically appears without screening.

The ad delivery systems are operated by platform operators, such as Google and Meta.

Google says the company, through a combination of assessments by artificial intelligence and humans, detects and removes advertisements that violate its ad placement policy.

Meta said it reviews advertisements before delivery mainly through an automated tool.

However, Hideyuki Nagasawa, secretary-general of Quality Media Consortium, an industry alliance that aims to improve the quality of advertising, said he believes that reviews by platform operators are extremely loose.

He said the companies’ ad revenues may decrease if they implement rigorous vetting.

Google, for example, depends on advertisements for 80 percent of its revenue.

Website operators can introduce tools to check ad content before publication, but they cost several millions of yen a year.

Visual examination is required as the final line of defense because some dodgy advertisements can slip through those tools.

Game8 Inc., which operates a leading game guide website, created an experimental site about Minecraft, a popular game, exclusively for children that does not display advertisements.

For its main site, the company is considering introducing a fee-based subscription for which ads are not shown.

Last autumn, the company assigned several employees to patrol the website and remove sexually suggestive advertisements through visual inspections.

Shunsuke Sawamura, president of Game8, said companies in the media industry can join hands to tackle the problem, but they are different in size and awareness.

Orangepage Inc., which operates recipe and other websites, issued an apology in March after a complaint was posted on the social media platform X about a sexually suggestive advertisement that appeared on one of its sites.

Naomi Harada, editor-in-chief at Orangepage, said the company had filtered out inappropriate advertisements and asked the ad delivery company to take down those that slipped through the checks.

But Harada said, “We feel like we have been playing a cat-and-mouse game.”

According to Rika Holden Nakamura, who lives in Britain and advises companies on advertising ethics, Britain’s guidelines on advertisement expressions prohibit sexually suggestive ones and those sexualizing children.

If there is a complaint from a consumer in Britain, an organization comprising researchers, lawyers and other experts reviews the ad in question and may order the advertiser to remove it, she said.

“Japan must establish specific guidelines or standards on extreme expressions and introduce a system that enables zoning concerning harmful advertisements,” Nakamura said.

Nagasawa also said the public and private sectors, with the involvement of the central government, must work together to formulate rules.

In Japan, it is not even clear which government branch is responsible for such efforts.

At an Upper House Budget Committee session in March, Takae Ito of the Democratic Party for the People said zoning is necessary to block sexually suggestive advertisements on websites viewed by children.

However, officials of the Children and Families Agency, the internal affairs ministry, the Digital Agency, the economy ministry and the education ministry all said the issue is not under the jurisdiction of their respective ministries or agencies.

Eijiro Mizutani, an associate professor of media law at Keio University, said advertisements that only suggest sexual situations often cannot be declared illegal, and that freedom of expression makes it difficult to regulate content.

Mizutani suggested the first step to deal with the issue may be the formulation of voluntary rules by advertisers, website operators, ad delivery companies and others concerned.

(This article was written by Midori Iki and Ryota Goto.)