Follow the trials and challenges of two girls aspiring to become the next greatest hero and villain. Yu is one of the candidates to become the next "Yuusha," while Mao is one of the candidates to become the next Demon lord. Mao and her two furry companions challenge Yu to a duel on a daily basis, but they always fail. Yu, on the other-hand, already holds a great amount of power. She just finds Mao to largely be an annoyance. (Source: MangaHelpers)

The volume release of EXP:0 only contains the last 7 chapters, relabeled as the "Dungeon Arc." The first 19 chapters were not published in print.