The Wonder Girls were introduced through a TV show titled MTV Wonder Girls. The first four episodes outlined the characteristics and profiles of each member and showcased their schedules for the day. Shortly after selecting Yeeun as the fifth member, the Wonder Girls held their first showcase in the MTV Studio. They performed a cover version of "Don't Cha" by the Pussycat Dolls as well as their own songs, including "Irony" and "미안한 마음" ("It's Not Love"). Sunye sang her version of Destiny's Child's "Stand Up for Love", while Hyuna performed a showcase of her dancing skills. The other three members — Yeeun, Sunmi and Sohee — performed a cover version of Janet Jackson's "Together Again".

In the year 2199, humanity eagerly waits for the dawn of the new century, following the end of a series of devastating magic wars. Word spreads that Ragna the Bloodedge, an SS-class rebel with the highest ever bounty on his head and a powerful form of Ars Magus known as the "Azure Grimoire", has appeared in the 13th Hierarchical City of Kagutsuchi. To collect the bounty and his Azure Grimoire, a motley array of fighters converge on Kagutsuchi