In pixiv, most of the submitted artworks are female oriented illustrations. Hence this tag is used a lot : a total of 388,676 illustrations were submitted on pixiv as of December 14, 2011.
This tag is mainly used for original creation, where it is seen mostly paired with the tag Original.
While the tag young girl is also used, The submission for "Girl" however far exceeds the former in terms of submission number, hence it is recommended to submit your illustration using the "Girl" tag instead of "Young Girl".
The Cat and The Girl
Boys and Girls
Youth Boys and Girls
Old Man and Little Girl
High School Girl
Girls With Glasses