In December 2015, TTS released its third special Christmas EP, entitled "Dear Santa". The album debuted at number two on the weekly Gaon chart of South Korea and has sold at least 60,456 copies to date. Seohyun wrote the lyrics to the title track "Dear Santa". As an effort to support music education for children in Asia, TTS contributed a part of the album's sales profits to a charity called "SMile for U", a campaign held between SM Entertainment and UNICEF.