Several Tsukiuta duet CDs will go on sale in late 2013 and early 2014.

The Tsukiuta series is a collaboration between seiyuu and VocaloP. Each CD features songs and mini voice dramas.
The CDs this December feature characters from months December to May. These characters form an idol unit called "Six Gravity". Each pair of characters has two CDs, each featuring a different VocaloP.

Official site for Tsukiuta: http://www.tsukiuta.com/index.html

Tsukiuta. Series Duet CD [VocaloP name] x Shounen-Gumi
Cast:
• Kaji Yuuki as Shiwasu Kakeru (December)
• Masuda Toshiki as Kisaragi Koi (February)

Inosencia
(Release date: Feb 28 2014)
With Nijihara PeperonP: Animate

Datte Mada Mada Avant-Title
(Release date: Dec 27 2013)
With Satsuki ga Tenkomori: Animate

Tsukiuta. Series Duet CD [VocaloP name] x Nenjuu-Gumi
Cast:
• KENN as Satsuki Aoi (May)
• Hosoya Yoshimasa as Uzuki Arata (April)

Rainy Day
(Release date: April 25 2014)
With ChouchoP: Animate

Tsuki to, Hoshi to, Maboroshi to
(Release date: May 23 2014)
With Nem: Animate

Tsukiuta. Series Duet CD [VocaloP name] x Nenchou-Gumi
Cast:
• Toriumi Kosuke as Mutsuki Hajime (January)
• Maeno Tomoaki as Yayoi Haru (March)

Koi Wasuregusa
(Release Date: Jan 24 2014)
With Machigerita: Animate

Hajimaru no Haru
(Release date: Mar 28 2014)
With Yuuyu: Animate