What makes Wag-Zak by Lovelyz notable?

'Wag-Zak' was notable for its unique a cappella style and received positive reviews for its catchy melodies and innovative vocal arrangements. The song showcased Lovelyz's artistic growth and contributed to their reputation as one of the leading girl groups in K-pop during this period. Released on January 1, 2018, 'Wag-Zak' marked Lovelyz's return to the music scene following their successful album 'R U Ready?' from 2017. At this point in their career, they were solidifying their identity within the K-pop genre while exploring more experimental sounds in their music.