DISCLAIMER: THIS ARTICLE MIGHT CONTAIN SENTENCES THAT ARE SUGGESTIVE IN NATURE, PLEASE READ IT AT YOUR OWN DISCRETION. MINORS ARE ADVISED TO READ IT ALONG WITH THE GUIDANCE FROM PARENTS OR GUARDIANS
R-18 or R18 is usually artworks posted are sexual (contents including but not limited to: couples having sex, fetishism, rape, and so on) in nature. However there are also illustrations that depicts extreme violence. Depending on how it's depicted, it might fall under the R-18G category.
The usage of this word comes the classification from Computer Software of Ethics Organization（shorten as ECOS or Sofurin）, where Eroge games that are produced in the market, which is labelled as an adult games are referred in the bishoujo game lineups as "R-18 Game" in order to differentiate them. Hence, the word "bishoujo game" itself purely refers to an all age game, where anyone in the market can purchase them without restrictions. However, the term "R-18 game" is rarely used, where people prefer to use the term "eroge" itself.
The R in the R-18 is an initial originated from the word rated.
The service requires age restrictions to be set on works which are not suitable to be viewed by minors.
Please be sure to set an age restriction when submitting any works to which the following apply.
R-18: Works containing images unsuitable for those under 18.
- Anything related to sex, or depicting it, contacting genitalia, or anything strongly resembling a sexual act.
- Violent scenes, ideas and memes are also highly dangerous and disturbing for minors.
While submitting illustrations related to R-18 is allowed, please note that a censorship (mosaic applying) is needed. Especially on private parts that are, but not limited to: the penis, vagina, scenes that depict sex (especially during insertion of the penis into the vagina) and many more. You are also advised to read the guidelines for further details about censorship or filtering.
Even with your viewing restrictions turned off completely, you may also look for illustrations without bumping through R-18 ones in between. Just enter your search term, followed by "-R-18" (remove the quotations) and you will be able to search for illustrations without the adult contents. If you find censoring to be pointless or oxymoron, please add "uncensored" (in Japanese, 無修正) tag onto your artwork just to be safe.
The proper way of setting R-18 illustrations
Without setting your view restrictions to sexual content, your submission will still be viewed as a work available for the public to view. Even with the R-18 tagged, it won't be considered as a work with adult contents without turning on the sexual content option in your information input page when submitting.
While it's okay to leave it up to the viewers to decide the overall legality of the content, you are highly advice to consider the overall situation and make the decision yourself instead in order to prevent unwanted confusions.
Taken from pixiv's help files
Q.Is R-18 related submissions allowed？
A. Yes. However, at your submit window, turn on sexual content at your view restriction option.
Deleting R-18 Tag
By turning on your viewing restriction and set it to sexual content, the R-18 tag will be automatically attached upon submission. The original submitter can actually remove the tag. Considering the option is already valid upon submission, removing the tag will still keep the restriction valid, and will not be available to view for minors below 18.
R-18G R-15 R-12/PG-12 R-1.8 R-16 R-17 R-17.9 (R-17.99) R-20 R-21 R-31 R-35 R-81 R-180 R-880 R-7 R-9 R25 R2-D2 Non R18 Not R-18 Unexpected R-18 R-18?
cosMo (BousouP) (There is a song titled "R-18" for Hatsune Miku, which is composed by cosMo.)