The group released their second mini-album, "Holler", in September 2014. The album debuted at number one on the South Korea's Gaon Album chart and also on "Billboard" World Albums. Reaching number one on the "Billboard" makes TTS the third Korean artist and the first female group to get more than number 1 on this chart. They previously reached number one, with their debut release, "Twinkle" in 2012. During an interview with Billboard, the three singers said: 