Bitna

Originally using the stage name Seungah, she debuted as a member of Sunny Hill on September 20, 2007 with their first single "Love Letter". Coinciding with the group's return to activities, on April 25, 2019, it was announced she would be promoting under the new stage name Bitna. In the spring of 2025, Sunny Hill departed from Kiya Music and later two of their three members announced that they had departed from the group.

Thus, only Bitna remained as the sole member of Sunny Hill. Nevertheless, Bitna remained as a member of Sunny Hill as the group would continue forward as a "one-member act". On July 25, 2025, Sunny Hill had its first release as a "one-member act" with the release of their 15th digital single "Let's Go" in which Bitna was the sole singer.