9 was released in two formats: a limited edition with an exclusive DVD and a regular edition. The DVD included with the limited edition of the album features a music video for "すべてへ", as well as a multi-angle version of the music video focusing on one of the five members of the band and a making-of documentary for the music video. The album was preceded by three singles: "Blue Flame", released in August 2011, and "Heart of Gold", released in September 2011 and finally Niji no Yuki on 21 December 2011.
After the release, the band embarked on four tours of Japan entitled Alice Nine "Court of '9'" #1-4. So far[when?] they have completed the first two of these tours with relative success in all areas of Japan, managing to sell out in many medium-to-large venues nationwide.
All lyrics written by Shou. A majority of the tracks were joint-produced by Alice Nine and Hajime Okano, except for Blue Flame and Heart of Gold (Produced by Alice Nine) and Niji no Yuki which was produced by Takamichi Tsugei.
9 peaked at number 12 on the Oricon Weekly Albums Chart and stayed on the charts for three weeks. Successful, but their lowest album ranking since their first in 2006 and considerably lower than the previous album, 2011's Gemini.