In February, Wanna One posted a series of teaser images titled 2018 Golden Age Begins. On March 5, Wanna One released their special theme track, "I Promise You (I.P.U.)" along with its music video. It was also announced that the number of preorders for their second extended play, 0+1=1 (I Promise You) has surpassed 700,000 copies, breaking the previous record set by the group. The album was released on March 19, along with the title track "Boomerang".