Monsters

Monsters are remnants of the Evil God that was defeated many years ago. They often have magic stones (or Crystals) inside of them.

= Monster Threat Level Ranking = Each Monster can be categorized by the level of danger that they pose and a corresponding rank can be given to them. A group of ten increases the threat by one level, and a group of a hundred by two levels.

Six-Legged Rats
A Six-Legged Rat is a type of animal species. It is an animal rather than a monster, meaning it yields no crystals. In the manga, the species has a crystal.

Appearance
The only encounter with the species mentioned describes it as a "small rat with six legs." In the manga, it appears briefly with no pupils, as well as tiny and oval-like ears and a white underbelly. A streak of a different color rests on its forehead, and the bottom of its claws are white.

Abilities
Six-Legged Rats are very weak and possess no magic. This may be in part due to the fact they are animals. In the manga, it contains a crystal once slain, suggesting it is a monster or that animals have crystals in the manga.

Crush Boars
Crush Boar is giant pig with a hammer-like snout; height is over two meters. Its alternatively translated as Crash Boar

Iron Ants
(giant ant with mandibles able to crush boulders)

Giant Bats
They are night creature with Echolocation skill.

Orcs
There orcs are type orcs that we think. Teacher has strong crystal taste of them.

Gourmet Orcs
They are subspecies of Orcs. They too have delicious crystal taste.

High Orcs
They are subspecies of Orcs.

Stone Spiders
(rock-like; has Advanced Poison Fang)

Giant Moles
(carnivorous; has skill Heat Sense)

Paralysis Cat
(has skill Conceal Presence)

Fiends
Fiends are servants of the Evil God.

Birds
Bird-type monsters do not have the skill Flight because it is a natural feature. However, they can have flight-enhancing skills. Air Current Sight is a staple of bird-type monsters.

Trivia

 * Blast Tortoise is a reference to the Pokemon Blastoise.