Overview
Futsukushii is formed by mingling the "u" in "utsukushii" with a breathe of sigh, hence "futsukushii".
Though it is thought to be a common case of typo or a net slang, it is actually originated from the anime series 「Yu-Gi-Oh! Duel Monsters」, where Seto Kaiba used that word in one of the episode (thought to be misheard).
In pixiv it is commonly used as a tag praising artworks that are thought to be beautifully drawn. Though it's also common to use this tag for Yu-Gi-Oh! related illustrations.
Though it is usually used as a template tag for artwork praising related tags, in the end it's tagging criteria is more to an artwork that are deemed worthy of this tag by the tag editors subjetively; hence there are a lot of bias cases towards people who submitted illustrations that recieves tag editing from the editors.
While it is also possible to tag your own illustrations with this tag, it might cause a lot of displeasing comments from the viewers. So you are advised NOT to do so.
The pros. and cons.
It is originally an evaluation based tag where it easily causes a battle of "attach or detach" game. More interestingly, there are also cases of outburst where people replacing the tag with "Utsukushii 美しい".
There are also disagreements like "Since it's just disgusting might as well just use "美しい" instead" or "It might cause people to think it as "腐つくしい (the kanji 腐 means rotten)"". However, there are also opinions like how using "美しい" might be so straight foward to the point it's embarrassing.
Whatever it is, illustrations that are so pretty you just sigh a breathe of relief do exist, no doubt.
Related Illustrations
Related Tags
Beautiful (美しい)