More than a hundred years ago, magic-using Fiends suddenly appeared, killed most of humanity, and claimed most of the planet's surface. The seven surviving nations are slowly attempting to take back their lost territory by raising armies of Magicmasters, who are all ranked according to their combat performance and achievements. The number one Magicmaster, Alus Reigin, decides to retire after fulfilling ten years of service to the nation of Alpha, but his superiors convince him to go on extended leave and conduct research at a Magicmaster school while attending as a student.
This works provides examples of:
- Antagonist Abilities: In addition to being giant beasts, Fiends are naturally able to channel mana and can get stronger simply by eating each other. In contrast, humans need years of training in order to control mana well enough to match Fiends. The fact that Gra Eater is disturbingly similar to Fiends is not lost to Alus as he worked a lot prior to the story just to keep it under control.
- Child Soldiers: Fourteen is the minimum legal age to become a Magicmaster, and Alus became one at age six.
- Crapsack World: The majority of the planet's surface is under the control of Fiends while humans are forced to live in a smaller territory under a barrier, and the majority of humanity was wiped out when the Fiends first emerged. While humans are mostly united in fighting the Fiends, there is still a lot of competition between the countries beneath the surface, which can lead to the governments getting desperate with unethical experiments.
- Leeroy Jenkins: In the second volume, the students of Alpha's Second Institute are supposed to hunt weaker Fiends near the barrier as practice, but some overestimate their ability and attempt to exit the designated area to hunt stronger Fiends. The principal, Sisty, predicted this and organized squads of more experienced students and Magicmasters to reign in the new students. While no one dies, some of the students got traumatized from nearly being killed by stronger fiends and lost the ability to use magic.
- Mercy Kill: All but one of Godma's test subjects lost their sentience and got reduced to being mindless puppets forced to fight on his behalf, with no hope of regaining their minds. The only thing the protagonists can do for the victims is to kill them.
- Military Mage: Originally, magic was mainly used to support people's daily lives, but the Fiend invasion forced humanity to focus on military applications for magic. This also led to the establishment of academies to train prospective Magicmasters. Elise, as a former Magicmaster from that time period, notes that this caused newer Magicmasters to be more limited in their imagination.
- Monstrous Cannibalism: Fiends become stronger by eating mana, but they can also generate mana, which means they can eat each other to become stronger. Fiends who get stronger this way are known as Variant fiends and usually require several skilled mages to take down.
- Power Equals Rarity: Inverted. Light elemental mages are rarer, but that also means there are fewer spells invented for that element, making it hard for light-elemental newbies to expand their moveset.
- Reality Ensues:
- When you throw a child into a battlefield due to his potential and talent to quickly bring out results, don't expect him to develop the same sentiment about fighting for humanity's survival and jump to help at the first opportunity, as that is exactly what happened to Alus, whose emotions are stunted.
- No matter how good a trainee is in training, they can still be traumatized by real combat against Fiends to the point where they'll either die in combat or become mentally unable to use magic ever again.
- Retired Badass: There's an unspoken rule that each country should only have one active single-digit Magicmaster at a time and that if a country gains two, one of them will have to retire in order to maintain the power balance between countries. Unfortunately for Alus, Alpha's brass won't allow him to retire because there's no new single-digit to replace him.
- Of course, as there are 9 Single Digits active at a time with only 7 countries to split them, it's inevitable that some countries will have two, and they tend to be the strongest countries, which are currently Alpha and Rusalca.
- Spell Blade: AWR (Assist Weapon Recovery) are weapons made to channel mana. These weapons also have formulas engraved on them to facilitate spell usage.
- Wizarding School: The Second Institute of Alpha is one of many schools for training students to become Magicmasters, and happens to be the one the main character, Alus, is enrolled in.