Mosaic censorship meaning: why Japanese adult games are censored

Mosaic censorship is the block of pixelation placed over genitals in Japanese adult games, manga, anime and video. It exists because of one sentence in Japan’s Penal Code. Article 175 punishes anyone who “distributes or displays in public obscene objects”, and for decades the explicit depiction of genitals has been the thing police and courts treat as obscene.

The law does not mention mosaics. It does not define obscenity either. The mosaic is a habit the industry built to stay on the safe side of a rule that has never been written down in detail.

This page explains what the term means, what the law says, how the practice reached games, who checks it, and why the English edition of a Japanese game is sometimes sold without it.

Key points

• A mosaic is pixelation over genitals. White-out and solid black bars do the same job.
• The legal basis is Article 175 of the Penal Code. It bans distributing obscene objects.
• No law requires a mosaic. The statute names no method and sets no standard.
• The test of obscenity comes from the courts. The leading case dates from 1957.
• Drawings are covered. Manga publishers have been convicted and arrested.
• Commercial PC games are reviewed by industry bodies. The first was founded in 1992.
• Doujin games are not reviewed by those bodies. The Penal Code still applies to them.
• Overseas editions can differ. The law concerns distribution in Japan.

What mosaic censorship means

The word describes the visual effect. A small area of the image is replaced with large square blocks of averaged colour, so the shape underneath cannot be made out. In Japanese the general word for this kind of modification is shūsei, meaning correction.

Mosaic is one method among several. The Comic Market Committee, which runs Japan’s largest self-publishing fair, tells its sellers that modification is done “with white-out, solid black, mosaic and the like”. All three are in use:

In a game, the modification is usually part of the finished image file. That matters later, when the question is whether it can be taken off.

The law behind it: Article 175

Article 175 of the Penal Code is headed “Distribution of Obscene Objects”. In the Japanese government’s English translation, its first paragraph covers a person who “distributes or displays in public obscene objects such as documents, drawings or recording media contained in electronic or magnetic records”. The penalty is imprisonment for not more than two years, a fine of not more than 2,500,000 yen, or both.

The same paragraph applies to a person who distributes obscene records “through the transmission of telecommunications”. The second paragraph extends the offence to anyone who possesses such objects, or stores such records, “for the purpose of distributing them for a fee”.

Three features of the article explain the mosaic.

1. It is about distribution. Selling, sending, displaying and holding stock for sale are covered.
2. It covers drawings by name. A game image is not exempt for being illustrated.
3. It does not say what “obscene” means. That was left to the courts.

Wikipedia’s article on censorship in Japan records that the provision dates from the 1907 code and that electronic records were added by an amendment in 2011.

What counts as obscene

The definition comes from the Supreme Court’s 1957 decision in the Chatterley case, which upheld convictions over a Japanese translation of Lady Chatterley’s Lover. The court used a three-part test: a work is obscene if it arouses and stimulates sexual desire, offends an ordinary person’s sense of shame, and runs against proper sexual morality.

That test is abstract. In practice it has been narrowed to one question, and the Comic Market Committee states it plainly in its guidance on related laws: obscenity “specifically means explicit depiction of genitals” and “specific depiction of the point of union”. The committee adds that the law applies to work aimed at men and at women alike.

A Tokyo lawyer, Takata Akio, set out the position in an article published on 27 May 2026. His summary makes three points.

• No statute requires a mosaic. It is a custom that developed in practice.
• There is no official standard for how much is enough.
• The working rule is about shape. Investigators reportedly do not treat material as criminal when the form of the genitals cannot be made out.

He describes the social rule that results as “properly modified is safe, not modified is out”. He also argues that a good deal of modified material could still meet the courts’ test, so a mosaic is a working convention and not a guaranteed defence.

Does Japanese law require mosaics?

No. This is the point most often misstated, including by developers answering questions on store forums.

Article 175 does not order anyone to pixelate anything. It bans distributing obscene objects, and a modified image is a way of producing something that is not treated as obscene. The mosaic is how the industry complies with the law, and the law itself never asks for one.

The distinction has practical effects. Because no rule fixes the size or density of a mosaic, the acceptable amount moves with enforcement. The Comic Market Committee tells sellers to take adult commercial magazines as their guide and to keep watching them, because standards there have tightened in recent years. It also warns that a full-colour, realistic drawing may still be judged obscene even with a mosaic, “depending on the extent and method of modification”.

Drawings have been prosecuted

A drawing has no real person in it, and the law makes no allowance for that. Three cases show how it has been applied.

• Misshitsu, 2004 to 2007. The publisher of the manga anthology Misshitsu was prosecuted in what is described as the first obscenity trial over manga. He received a suspended prison sentence, reduced on appeal to a fine of 1.5 million yen, and the Supreme Court upheld the verdict in 2007.
• Core Magazine, July 2013. Anime News Network reported the arrest of the publisher’s head editor and two others over a manga magazine and a photo magazine said to be insufficiently censored. Both carried an 18+ mark and both used mosaics. Police said they had warned the staff beforehand.
• Rokudenashiko, 2020. On 16 July 2020 the Supreme Court rejected the artist Megumi Igarashi’s appeal against a fine of 400,000 yen for distributing 3D scan data of her own body, as Anime News Network reported. Lower courts had acquitted her over a separate display of her artwork.

The Core Magazine case is the one the industry remembers. The Comic Market Committee cites it by date in its guidance. It showed that an 18+ label and a thin mosaic were not enough.

How the rule reached games

The rule reached games through a police case in 1991.

Writing for Famitsu in October 2023, the writer Morise Ryo gives this account. A junior high school boy in Kyoto shoplifted an adult PC game, believed to be Saori. On 25 November 1991 the juvenile division of the Kyoto Prefectural Police searched the offices of two software companies in Tokyo, seized close to 300 titles and arrested three people. The charge was possession of obscene material for the purpose of sale.

The consequences followed quickly.

1. Distributors stopped handling adult PC games for a time. Some games in development were delayed or released with content removed.
2. An 18+ sticker system started on 1 April 1992.
3. A review body was formed. The Ethics Organization of Computer Software, known in Japan as Sofurin, was formally established at its first general meeting on 20 November 1992.

Our short history of adult games covers the years around this in more detail.

Who checks a game today

Review of adult games in Japan is self-regulation. Wikipedia’s survey of video game content rating systems describes the arrangement.

Two details are easy to miss. Ratings are not required by law. And doujin work is outside the review system while remaining inside the criminal law: the same Wikipedia article notes that distributing obscene material can still be punished under Article 175.

Stores add their own layer. A download store or a fan subscription site that sells adult doujin work sets a modification rule for what it will list, and those rules move too. The lawyer’s summary cited above reports that the fan site Fantia tightened its mosaic guidelines in May 2026 and then went back to the previous standard while it prepared a new one. We cover that site’s payment side in how to pay on Fantia.

Console games fall under a separate board with its own limits, explained in CERO Z explained. For the vocabulary used here, see adult game terms explained and doujin game meaning.

Why overseas editions are sometimes uncensored

Article 175 governs distribution in Japan. An edition published by a company in another country is sold under that country’s law.

Wikipedia’s article on eroge puts the result in one line: scenes carry censorship of genitalia, and games become uncensored “only if the game is licensed and released outside Japan”. Whether a particular game does depends on three things.

• Whether unmodified artwork exists. If the artist drew the mosaic into the only surviving file, there is nothing to restore.
• Whether the Japanese rights holder agrees. The decision is the developer’s, and some decline.
• Where the edition is sold. A store has its own rules about explicit content, set out for the two largest in DLsite vs Steam.

So a mosaic in an English release is not always a decision by the English publisher. It may be the only version of the artwork there is.

What this means for players and developers

For a player, the mosaic says where a game was made for sale. It does not say how explicit the game is, and it is not a sign of a cut or damaged copy.

For a developer outside Japan, three points follow.

1. Selling into Japan means meeting Japanese expectations. A Japanese store will apply its modification rule to a foreign game as well.
2. Keep the original files. A game drawn with modification on a separate layer can be released in both forms.
3. Do not treat the standard as fixed. It has tightened before, and the stores revise their rules without much notice.

The wider set of decisions is covered in how to make an adult game.

What is still unknown

• How much modification is enough. No official standard exists, and the sources above say so directly.
• Where the mosaic technique began. Accounts online trace it to adult video, and we found no reliable source that dates it.
• The exact standards of the review bodies. We did not find the modification rules of the Ethics Organization of Computer Software published in a form we could quote.
• How Article 175 applies to a Japanese company selling an unmodified edition only abroad. We found no court decision on the point.

How this page was put together

The text of Article 175 is quoted from the Japanese government’s English translation. The Comic Market Committee’s guidance was read in Japanese on its own site, and the passages quoted are our translations. The account of the 1991 search and the founding of the review body follows the Famitsu article. Case details come from the news reports and reference articles listed in the sources.

Nothing here is legal advice. The studio is not based in Japan and has not submitted a game for review there.

This page was written on 12 October 2026. To report an error, see the corrections standard.