An artwork sharing website in Japan. Predominantly features anime themed works. You could possibly consider it the Japanese version of DeviantArt like others have said.
Pixiv is more lenient on their policies with adult content in comparison to DeviantArt however. Though the site offers a filter that you have to disable, Pixiv does contain artwork that can definitely be considered not suitable for children, and not all of it may be filtered.
I have labelled this site with "opinions" because some of the artwork you may find on the site (especially by 18+ artists with the filter disabled) may be considered "Gruesome or shocking" to some.
Overall, it's a good website with a collection of some really great aspiring artists.
Great site overall, as others have said it's like Deviantart. But there are a large amount of pornographic works and some of them involve images of children. This is definitely not a site safe for children, so keep the content filters on.
I've only used this site for a less than 1 hour, but already I have noticed several thumbnails of images depicting sex with a child... That seems to be quite acceptable in Japan, but where ever it is, it's not!
That's the kind of shocking thing you will see on this site if you turn the mature content filters off.
There are a lot of very skilled illustrators and designers in Japan, and a lot of them use this site because most of them are not confident of their English skills to join international site. It's like a Japanese counterpart of Deviant Art. Great site for art enthusiasts.