On October 10, 2016, JYP Entertainment first confirmed details about Twice's upcoming EP titled
Twicecoaster: Lane 1 by releasing a promotion time table through the group's official homepage and
SNS accounts, showing their promotion schedule beginning October 10 until the release of their album which was slated on October 24. On October 11, Twice uploaded an intro video which depicts the group returning to their dressing rooms following a performance of their previous single "Cheer Up", before each member received a text message which leads to them frowning and making a pose forming the word "TT". On October 12, the group released an album preview revealing its contents and packaging. On October 13, Twice uploaded an image of the album's track list, revealing its lead single to be "
TT" and featuring seven songs in total. An image titled "Twice MV Universe" was also released on the same day, suggesting that the in-universe events of the upcoming music video for "TT" would be connected to the music videos of Twice's previous singles "
Like Ooh-Ahh" and "
Cheer Up". Twice uploaded their first group teaser photo on October 14. A second group photo was uploaded later on the same day depicting the members sitting on chairs which are arranged similarly to that of a rollercoaster. On October 15, two group teaser images featuring
Jeongyeon,
Mina,
Nayeon, and
Momo were released. On the same day, the group released a second album preview revealing that two versions of the album: apricot and neon magenta, are available. The two available versions for the album are references to Twice's official colors which they announced earlier in September. On October 16, two group teaser images featuring
Jihyo,
Tzuyu,
Sana,
Chaeyoung, and
Dahyun were released. On the same day, members Mina and Chaeyoung made an appearance on the
2016 KBO League held at the
Jamsil Baseball Stadium in order to throw the ceremonial first pitch for the match between
Nexen Heroes and
LG Twins, wherein they showed the "TT" pose, attracting attention. On October 17, three individual teaser films featuring Nayeon, Jeongyeon, and Momo were released, which depicts each member encountering their own disappointing situations which leads to them forming the "TT" pose. This was followed by the teaser films featuring Sana, Jihyo, and Mina released on October 18. On October 19, the last batch of individual teaser films featuring Dahyun, Chaeyoung, and Tzuyu were uploaded. In celebration of Twice's first anniversary since debut, the group unveiled the EP's seventh track "One in a Million", the song they dedicated to fans, through a live broadcast on Naver
V Live titled
Twice 1st Anniversary V on October 20 at 22:30 KST. On the same day, they uploaded the first music video teaser for "TT", depicting a Halloween-themed concept and featuring two children entering and exploring a gloomy mansion for
trick-or-treat. This was followed by a second teaser clip uploaded on October 21, which featured the members greeting the children while also revealing a part of the song's opening verse and its choreography. On October 22, the group released pastel-toned individual teaser photos for each member. It was also revealed that the physical album has nine random CD covers featuring the each member of the group. The following day, Twice released a highlight medley featuring audio snippets for all the songs in the EP alongside a series of choreography teasers which illustrate the dance moves of each member, for "TT", in characterized diagrams. The album was officially released on October 24 at 12AM KST. It was also released as a digital download on various music portals. == Composition ==