The group's first album as an eight-member group, their fifth Korean studio album "Lion Heart", was released on August 19, 2015. The album reached number one in South Korea, and at number 11 in Japan. The album sold over 145,000 copies in 2015. It produced three singles; the lead single "Party" reached number one on the Gaon Digital Chart, and number ten on the Japan Hot 100. Following the release of "Party", Girls' Generation appeared on the "Billboard" Social 50 at number 44 on August 1, 2015. The following week, the group's position on the chart rose to number 22. The follow-up singles "Lion Heart" and "You Think" were made available in conjunction with the release of the album. They charted at numbers four and 30 on the Gaon Digital Chart, respectively.