Hyperdimension Neptunia Re;Birth1 has debuted on Steam in Japan today. In North America, the game has been updated to include the option of Japanese subtitles.
Idea Factory has also released some additional content in the form of a Deluxe Pack. It includes a digital soundtrack with 30 songs and a tracklisting in both English and Japanese, a 29-page digital art book, plus an exclusive PC theme featuring two wallpapers and an icon set. The Deluxe Pack does not include the game, and it is being sold for $9.99.
See samples of the PC theme and artbook in the following gallery.