Lee Yeo Reum, better known by her stage name Goo Seul, is a South Korean singer. She made her debut in the South Korean girl group Girls'Alert under Roots Entertainment om May 25th 2017, with the single "Dreamgirls". Lee Yeo Reum, better known by her stage name Goo Seul, is a South Korean singer. She made her debut in the South Korean girl group Girls'Alert under Roots Entertainment om May 25th 2017, with the single "Dreamgirls".