Song Jieun's agency revealed on December 2 that she would be releasing her first solo EP, Twenty Five, in Japan. 

This EP was first released in Korea on October 14 and a Japanese version of "Twenty Five" will be included in the Japan release.

The Japan single will also include songs from her new album such as "Don't Look At Me Like That", "La Boum" and songs from her solo album, "Vintage", "Hope Torture" and more.

Her first self-composed song, "Star," will also be included as well.

Two different versions of this EP will be released in Japan, one showing a more cute and girly side and one a more sophisticated side.

The Japanese track list includes:

1. "Pretty Age 25" (Japanese Version)
2. "Don't Look At Me Like That" (Japanese Version)
3. "La Boum" (Japanese Version)
4. "Vintage feat. Zelo" (Japanese Version)
5. "Star" (Korean Version)
6. "Pretty Age 25" (Instrumental)

• DVD Tracklisting

1. "Pretty Age 25" (Music Video) (Japanese Version)
2. "Pretty Age 25" (Music Video) (Japanese Version) (Making Of)

Song Jieun is the main vocal for the group SECRET and debuted in 2009 under TS Entertainment.

She also began solo artist activities and also sang for many soundtracks for dramas.

She also hit number 1 on the Gaon charts as a solo artist with her 2nd single, Going Crazy.

She has also done a bit of acting in dramas from cameos to short roles as well.