In a post-apocalyptic polluted earth overrun with mutated beasts called Filth Monsters (Contaminoids in Funimation's translation), humanity is forced to live in large mobile cities called Regios and learn to use weapons called DITE and harness the power of K to defend themselves. In the Academy City of Zuellni, a new group of students are hoping to start a new life without the constant fear of being dragged into an actual war. The twenty first platoon has recently been made by a teenage boy named Chandler (or simply Chand) Rekler who is a precision duel wielder who was formerly a part of the tenth platoon. He seeks to regain his respect and honor by teaching these new kids, and their fellow students, how to do things properly. Along the way they shall be tested by not only humans but a secret conspiracy (which will take a back seat to our actual fights for a awhile and its a plot point for later in the story) to destroy Zuellni and take its resources for another city. To win the tournament and to stop this war from happening the twenty first platoon will need all of its strength and courage. But do they have enough to survive?
Regios Large Mobile cities created by humans to live after Earth atmosphere became too polluted to live. Each city is named after the Electronic Fairy that controls the Regios. Most Regios avoid Filth Monster as much as possible but with the exception of Glendan, which does the opposite as it constantly finds monsters. There are two different kinds of city’s; Academy Cities & General Cities. Academy cities like Myath, Zuellni, and the former Gandoweria are places where students from different areas come to learn & study. General cities are the main cities where most of the population lives. Different types of cities are under the title of general city. These include Trade cities, transport cities and the Proto-City Glendan. Due to a treaty, only Regios of the same type are allowed to have a match with each other. Proto-City Lance Shelled Glendan: The most powerful city in the world due to its regular encounters with Filth Monsters of all levels and was the birthplace of the Military Arts, which most other cities practice today. The Twelve Heaven's Blades are found here under the command of the Glendan Royal Family.
- Academy City Zuellni: A University City governed by its students. This is where the manga/light novel/anime takes place. Its Electronic Fairy takes the shape of a pale blue, young girl.
- Academy City Gandoweria: A former city that was overrun by Pollutant Beasts not long after their victory over Zuellni two years ago. Its Electronic Fairy takes the form of an goat-like creature and is currently running amok as a Haikizoku.
- Sheniebel: The city Nina Antalk grew up in, currently the only city with the Fairy Copy System which is capable of making new Electronic Fairies. Like Glendan, Sheniebel also has a royal family, which Nina is the heiress of, as seen in the manga of Chrome Shelled Regios.
- Academy City Myath: An academy city like Zuellni, its electronic fairy takes the form of a red bird. In the anime, the military capabilities of this city are shown to be poor, perhaps even worse than that of Zuellni, as when attacked by a mature filth monster no resistance from the residents of the city is put up.
- Transport City Yoltem: The original home city of Mayshen Torinden, Mifi Rotten and Gerlni Naruki, according to the manga. All roaming buses eventually return to Yoltem and most travelers will encounter it during their travels. Only its Electronic Fairy knows the current location of every regios.
- Trade City Santoburug: The city Kalian Loss and his sister Felli grew up in. Their family holds significant positions and weight in the city, and is the Regios
- Electronic Fairy Special Artificial creatures that control the Regios. Created by scientists as a two-way solution of having an AI performing the many functions of a Regios while having a mind of a human for maintaining and controlling the Regios, they are the most important asset of every city. Without them, the city would die. On the other hand, the Electronic Fairy will also die if it does not have Selenium, a special ore that has many Regios fight each other for their city's survivability. An electronic fairy whose city has been ruined turns into a Haikizoku, a being which is capable of greatly enhancing a Kei users power, but the user will be filled with endless hatred towards pollutant beasts.
Filth Monsters/Pollutant Beasts/ Contaminiods Monsters roaming the polluted earth outside the Regios. In the novels, Layfon and Kalian encountered an enormous and extremely powerful one that speaks the human language, according to it, pollutant beasts are also a creation of human. Their main food sources are the pollutants they breathe into the atmosphere, humans and themselves if the former cannot be obtained. They have many forms and sizes: Larva: The first state of the Filth Monsters. Ravenous feeders, they will eat any living thing they find. They are overwhelming in number, although easily dispatched by skilled Ki users and expert Military Artists. They prove to be difficult for the students of Zullini when they first encountered in the novel. It would appear that there are two different types of Larva stage Pollutant Beasts. Some of the Larva stage forms are able to fly, while others seem to only be able to move along the ground. In the anime, it appears as if the larva can shift between the two when Zuellni is attacked from below by Larva stage Pollutant beasts. Some sprout wings and attack the Academy City from the air. It is unconfirmed whether or not these mature into different types of queen stage Pollutant Beasts.
- Queen: A Filth monster that lays eggs that hatch into Larva. This is the second form of Filth monsters. Based upon the anime, (With the exception of Limbeekun) these Pollutant Beasts live, and lay their eggs underground. It would also appear that when they mature enough, they travel above ground and latch themselves onto a nearby rock or pillar. They then molt inside of their current skin into a mature form, and may wait until a meal passes by.
- Mature: A Filth Monster who has, generally, moved past its ability to procreate (although the transformation types seem to be the exception to this rule since they seem to have found an abnormal way to reproduce), the longer they live the more powerful they become. In their Mature state, Filth Monsters are able to fly. This is the third form of filth monsters. In Glendan there exists a tradition that if a Mature Level Filth Monster is engaged by the Heaven's Blade Receivers and manages to escape alive, then it is given a name. In the anime, one such example is Limbeekun, though it was defeated by Lintence, Savaris and Layfon when it attacked Santoburug at the beginning of the first episode, it has a counterpart in the Light Novel called Behemoth.
- Note: In the anime, Dainsleif is a powerful Pollutant beast that is from the Zero realm. It does not appear to be similar to the Pollutant Beasts in the world of Regios because its body is much different. This may be due to an extreme maturity phase or because of Ignacius' design.
DITE DITEs are the weapons used by Kei users. DITEs are small transformable devices when unused that turn into a weapon which the user activates it by saying "Restoration". Many types of weapons can transform from DITEs including crushing swords, spears, rifles, staves, katanas, and many more. Some DITEs are capable to switch to many different types of weapons. The color of the DITE ore is not random; different colors give different properties to the weapon. For example, Nina's iron whips uses black DITE ore, which has good density with a decreasing conductive rate. Green and white DITE ore is used for speed-based weapons, which was suggested for Layfon to use. People who work on the development of DITEs are called DITE Technicians in Glendan and DITE Mechanics in Zuellni.
- The Heaven's Blade: The most powerful DITEs wielded by the "Heaven's Blade Receivers" Whom serve under the Royal Family of Glendan. There are twelve in existence at the maximum since there are only twelve dites. They do not have a fixed format, volume or weight as weapons, upon appointment of a new wielder they can be reformatted by Glendan's DITE Technicians to take on the shape and abilities of the weapon the receiver desires. Another instance was when Layfon's Psyharden Katana and Heavens Blade (sword format) merged to take on a Katana format in the anime. In the novels, the dites themselves are passed down from generation to generation, they can withstand the monstrous quantity of kei that a heaven's blade receiver produce without breaking like a normal dite would. Layfon had problem wielding a normal dite after using a Heaven's Blade because he has to restrict his flow of kei or else the dite would explode.
Kei Source of power for Martial Artists. Kei users are special since they have an organ within their bodies that produces this energy and Kei users can use it in many ways. There are different types of Kei each with its own qualities. In the Anime it is said that the "Heaven's Blade Receivers" have "monstrous" amount of kei that makes even the strongest kei users look weak (e.g. Layfon beat Haia and Gaherd easily) External Type kei: Used for attack. This kei is used in the form of a blast to affect surrounding materials.
- Internal Type kei: Used for defense and regeneration. This kei is used to strengthen parts of the body during battle or to speed up regeneration. Layfon claims that it's bread and butter for Heaven Blade's Receivers to fight continuously for a period of days without getting tired or unfit for battle.
- Psychokinetic kei: Users of this kei (who are also called Nen-I users) are able to communicate telepathically as well as move objects around telekinetically. The downside of this kei is that those who are able to use it cannot use External Type kei or Internal Type kei because their psychokinesis is a fusion of both Internal and External kei. A person must be born with a special physical constitution to use this kei, while the other two can be utilized by anyone with training and a certain level of kei.