[1] The EP contains five songs which feature vocals from the original line-up (G)I-dle, Madison Beer, and Jaira Burns plus a variety of influential singers, such as Bea Miller, Wolftyla, Lexie Liu, Kim Petras, Aluna, Bekuh Boom, and Annika Wells and with Twice members Jihyo, Sana, Nayeon, and Chaeyoung.

[3] On September 5, K/DA confirmed that they are working on a collaboration with Seraphine, a fictional virtual influencer after fans have speculated since she has been posting on Twitter, Instagram, and SoundCloud and art style seemed in line with other characters from the game.

[6] Simultaneously, Riot released the first episode of their new web comic series titled K/DA: Harmonies showing behind-the-scenes of the group's recording process, members encounter, experiences and adventures.

[15] On October 12, Riot Games released new skin for K/DA's members Akali, Evelynn, Ahri, and Kai’Sa including Seraphine.

In TFT, Feather Knight, Fluffy Tail, Whining, Horn, and Flash will appear in a new form that based on K/DA's concept.

[20][21] Riot Games also conducts outdoor advertisements by accessing the QR code to 'K/DA Comeback Support Event' displayed on the billboard near Samseong station, Express Terminal and entrance to the Starfield COEX Mall, which are known as spots where idol advertisements are held.