T-ara N4 was the first official sub-group of South Korean girl group T-ara, composed of Eunjung, Hyomin, Jiyeon and previously Areum until her departure from the main group in July 2013. The sub-group only released an EP, Jeon Won Diary in April 2013.

In late March 2013, T-ara's agency Core Contents Media were in the midst of forming a new unit from the group with the members Eunjung, Areum, Jiyeon and Hyomin. The unit's name, T-ara N4 (which stands for "T-ara Brand New 4") was revealed April 12, 2013.^[1] T-ara previously tried sub-units with the promotions of their sixth Japanese single "Bunny Style!", in which the B-sides were sung by units of two and three members; however it would be their first time official unit activities.^[2]

T-ara N4's debut single, "Jeon Won Diary" (전원일기; Jeon-won Ilgi), was inspired by the 1980s South Korean drama of the same name.^[3] Produced by Duble Sidekick, the song is said to have "funky and intense" dance music combined with elements of hip-hop,^[4] with the main motif of "Jeon Won Diary" about breaking away from the same everyday routine.^[3]

On July 10, 2013, Areum left the group to pursue her solo career.^[5] Core Contents Media announced that Dani would replace Areum's positions in T-ara N4 only, which Dani originally revealed to joined as the ninth member of T-ara in 2012^[6][7] As of October 2014, their agency initiated Dani to not be part of T-ara N4 and would continued her training under the agency.