The New York-based headquarters of the United Nations Entity for Gender Equality and the Empowerment of Women — known as UN Women for short — is protesting against Japanese newspaper The Nikkei over a full-page ad it ran on April 4th.

Huffington Post Japan reports that the advertisement for the fourth volume of Towawa On Monday violates the agreement the paper made to participate in the Unstereotype Alliance, a group dedicated to eliminating harmful stereotypes in society. The advertisement featured the main character of the manga Ai-chan in her school uniform.

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“Stereotypes regarding women and girls are a major factor in preventing the realization of gender equality,” Kae Ishikawa, director of UN Women's Japan office told Huffington Post Japan. “Because advertisements have a major influence on the formation of societal norms… the advertisement in question is a violation of the [The NIkkei‘s] agreements to participate in the Unstereotype Alliance.”

"A manga advertisement that portrays an underaged woman in a school uniform in a sexualized manner plays a part in strengthening the stereotype that ‘high schools girls should be this way.’ It also holds the danger that it can encourage men to sexually exploit underage women. UN Women is opposed to the publishing of such ads. It goes against the memoranda exchanged between [The Nikkei] and UN Women."

Towawa On Monday is an ecchi series, a genre focused on playfully sexual content. The manga focuses on a middle-aged salaryman who befriends a large-breasted high school girl. In fact, her name Ai-chain is a pun based on her I-Cup bra size.

"The manga sexualizes underage high school characters," JIbu Renge, Associate Professor at the Tokyo Institute of Technology told Huffington Post Japan. "By publishing the ad, The Nikkei seems to be promoting adult men sexualizing high school girls. By publishing the ad on such a large platform, many people who have no desire to see its imagery were forced into doing so. The issue, in this case, is not the existence of the manga itself, but the audience to which it was advertised."

The hashtag #getsuyoubinotawawa trended on Japanese Twitter with the announcement of the news, with many users upset that the UN would be interfering with something that is a domestic Japanese issue. It is not the first time the series has been a part of controversy either, with its first episode previously removed from YouTube for violating YouTube's Community Guidelines.

Kodansha, the publisher of the series, issued a statement due to the controversy it developed online. "The advertisement was placed in conjunction with the release of the new book in order to attract new readers. We take your comments seriously and will give full consideration to the future development of our advertising."

Ishikawa told Huffington Post Japan that she was told by a Nikkei representative that the ad had been reviewed by many people before publishing, but hadn't been identified as a problem. "Without an explanation from the company, I am not convinced that we will continue to work with them to promote gender equality through the power of advertising," Ishikawa said.

An anime adaptation of Towawa On Monday was produced with twelve episodes and is currently available to stream on Crunchyroll.