GSC has setup a campaign to promote their newly announced Nendoroid Petite: Hatsune Miku Selection a few days ago, that says:
We are currently running a special Twitter campaign as a part of the recent announcement for Nendoroid Petite: Hatsune Miku Selection. If we manage to reach 3939 tweets that include the #nenpuchi_mikusele hashtag, a special set of Twitter skins including a background, icon and header image will be released for everyone to enjoy!
… and yesterday, it has reached more than 2000 tweets, so GSC has decided to release 3 out of 6 Twitter themes (or skins, as they called it) to be used to decorate your Twitter profile page.
Well, what are you waiting for? Head directly to the source page to download the cute Twitter themes.
P.S: We chose the Aku no Musume (Daughter of Evil) theme for our Twitter profile. XD