It is the dark century and the people are suffering under the rule of the devil, Vandel, who is able to manipulate monsters. The Vandel Busters are a group of people who hunt these devils, and among them, the Zenon Squad is known to be the strongest busters on the continent. A young boy, Beet, dreams of joining the Zenon Squad. However, one day, as a result of Beet's fault, the Zenon squad was defeated by the devil, Beltose. The five dying busters sacrificed their life power into their five weapons, Saiga. After giving their weapons to Beet, they passed away. Years have passed since then and the young Vandel Buster, Beet, begins his adventure to carry out the Zenon Squad's will to put an end to the dark century.

Two OVA episodes are bundled as DVDs with each of volumes 6 and 7 of the manga. The first OVA is a prequel story written by the manga's author. Before the beginning of the main story, Rea and Chihiro have already met at a certain place: an outdoor hot-spring bath. The second OVA takes place after the series (effectively episode 14). The Furuya family finds a mysterious young girl hiding under the household temple.

Extra episode included on BD/DVD vol. 6; effectively episode 13. Despite their decaying bodies, Rea’s zombie power comes in handy both at school and at home, and Babu gets interested in another cat—although this particular feline is one of the living. (Source: FUNimation)

Arslan Senki (TV): Dakkan no Yaiba retells the events of the series' first 13 episodes, summarizing the events that transpired from Arslan's escape with Daryun, to their time in the Peshawar Citadel.