Mitsuki Aya, who played fighting games competitively as a child, transferred into Kuromi Girls Academy in order to become a proper lady. Upon meeting Yorue Mio, known throughout school as the White Lily, Aya is blown away by her grace and elegance. To her surprise, however, she later finds Mio playing a fighting game online and coarsely trash-talking her opponents after school. And if that wasn't perplexing enough, this unladylike version of Mio challenges her to a duel.

[Source: AniDB]