NMIXX gave a first listen to part of its new album in a cappella a week before its comeback. On the afternoon of the 11th, NMIXX released an a cappella highlight medley for its sixth mini album "Strange Muse" on its official social media channels. The a cappella highlight medley is the group's signature teaser content released with every comeback, previewing new songs using only the voices and harmonies of the six members — Lily, Haewon, Sullyoon, Bae, Jiwoo and Kyujin — without instrumental accompaniment. In this video, the members, dressed in all black, sang parts of three songs: the title track "Birthday Wish," track 2 "Kerosene" and track 3 "RudE TaLK." Their agency JYP Entertainment explained, "By stacking harmonies with only the six members' voices, they proved the vocal skills of an all-rounder group." The album also includes unit songs not revealed this time: "Sing to the Moon" (Lily and Haewon), "Hot 'n Unbothered" (Sullyoon and Bae) and "WHIP" (Jiwoo and Kyujin). These are NMIXX's first unit songs, and the members took part in creating them. "Strange Muse," with six tracks in total, will be released at 6 p.m. on the 19th.