Shuukan Shounen Girl

Synopsis

Each of this manga's chapters features a new girl. The first chapter starts out with Ichikawa, who mysteriously has a shounen manga show up on her torso each week, a malady she shares with her male classmate, manga-fan Aoi. The second girl, Kawamura, notices that a boy in her class is suddenly being duplicated! (Source: MangaHelpers)