"Ssangdungi Seongjwa" is an original Korean song by Team Eternal Harmony featuring SeeU. This song is the first part of "Constellation Gemini Project" (쌍둥이 성좌 프로젝트) by Team Eternal Harmony. It tells the story of two twins born to a woman, but they were stolen from their mother by the queen of the country, as they were selected to be the heirs to the king and his wife, who could not bear children. The mother of the twins sought revenge and tried desperately to retrieve her children, but the king refused, sending her away.