This place you ought to be careful about, if you decide to go collect the free swimsuit for the Terai Yuki 2 figure:

http://www.pixiv.net/member_illust.php?mode=medium&illust_id=14984295

Reason for my warning:  some mature content featured in the advertising and blurbs could flash on your screen.

Scroll down to the comments by the creator of the picture.  You will see a link.  click on that link.  It takles you to another webpage which tells you you are about to collect something which is not hosted on the Pixiv website, and asks whether you really want to continue offsite.  If you do, then click the link for the download.

Eternal Hobbyist