Merry and Happy is the reissue of South Korean girl group Twice's first studio album, Twicetagram. The Christmas-inspired album was released on December 11, 2017. In addition to the original track listing, it has two new songs: the first track is titled "Heart Shaker" and the eponymous second track "Merry and Happy" was written by Park Jin-young. The album and "Heart Shaker" debuted at No. 1 on four charts of Gaon-Album Chart and Digital Chart and Social Chart respectively, while "Merry and Happy" entered and peaked at No. 24 on Digital Chart. Twice performed both "Heart Shaker" and "Merry and Happy" on music programs-Music Bank, Show Music Core and Inkigayo on December 15–17, respectively. The music video of "Merry and Happy" was set for release on December 21, but was uploaded online the next day instead in respect to Kim Jong-hyun, whose burial service was held on December 21.