Girl's Day () is a four-member South Korean girl group formed by Dream Tea Entertainment in 2010. The group members are Sojin, Minah, Yura, and Hyeri. Girl's Day started as a five-member girl group with Sojin, Minah, Jisun, Ji-In, and Jihae. After Jisun and Ji-In left, Yura and Hyeri became members. They reason why they left the group is that Jisun is going to study music more and Ji-In wants to act. Jihae wanted to concentrate on studying. 