“Oh Mymy: 7s” serves as a pre-release track, signaling ahead the official debut of TWS. The song starts with a string intro that samples a melody from Robert Schumann’s “Kinderszenen (Scenes from Childhood)” but then quickly changes the atmosphere through powerful bass and synths.

The “7s” in the title means seven seconds so that TWS members can show what kind of person they are and present a variety of charms in just seven seconds, as they said in the lyrics.

The prologue video accompanying “Oh Mymy: 7s” offers a glimpse into the TWS members' journey as trainees to their evaluation day in front of esteemed figures from the music industry, including HYBE’s chairman Bang Si Hyuk, PLEDIS’s producer Han Sung Soo, senior group SEVENTEEN, and music producer BUMZU.