FTISLAND brings the 16th single. The title track "JUST DO IT" is written and composed by Lee Hong-gi while "EMPTINESS" is written and composed by Choi Min-hwan. This edition includes a bonus DVD with a music video, making-of, and a performance from "Arena Tour 2016 -Law of FTISLAND: N.W.U-," which is shot from different angles at their concert at Tokyo Metropolitan Gymnasium. Comes with an application code (1) (valid only in Japan) and a trading card randomly selected from six kinds. *CD contents partially vary depending on the edition.