T-ara N4 gave a hint that the other members were preparing another subunit.

On April 22, the T-ara subunit held a press conference at Gyeonggi Goyang Art House, and Jiyeon revealed, "The rest of the T-ara members Soyeon, Boram, and Qri are preparing another unit in Japan."

She added, "The current T-ara N4 members had a hip hop stage in July at the Japan Budokan concert. The concept of T-ara N4 began then and after the concert, we told each other that we'd go on stage again if we had a chance. We're practicing the T-ara N4 song, of course, but we're also working with the other Japanese unit on T-ara's new song as a full group."

[Thanks to everyone who sent in this tip!]