Yoon Byul

In December 2014, Yoon Byul began promoting with the girl group BaBa under the stage name Dayul. She officially debuted with the group on March 24, 2015, with their first single, "Sergeant Kim's Return from Vietnam". She silently departed from the group in May for undisclosed reasons.

On August 24, 2015, she was added to Leader'S as a replacement for member Park Seol. She officially debuted on September 30 for the groups single album "Leader'S Story". On October 12, TGN Entertainment announced that Yoon Byul along with Han Seoyeon and Sandy had left the group for personal reasons and that Leader'S had disbanded.