The novel takes place in a fantasy world inhabited by a wide variety of different races and creatures. The central conflict of the world appears to be that of the titular hero Ziral versus the demon king and their forces. The currency of the world is known as marls which take the form of coins.
Characters within the world have levels akin to those found in a role-playing game, a numeric value which limits one's capabilities. Like in an RPG, killing enemies can grant experience to help level up. The concept of mana within the world seems to mirror that of spirit energy, as other characters view Kazuya's spirit energy as mana and Kazuya is able to apply teachings and theories regarding mana to his spiritual techniques.
Goblins (小亜人,,Goburin) are hostile humanoid creatures part of the Demon King's forces. They can also be found within the dungeon Minadonari. Goblins are muscular humanoids, with long noses, clawed nails, large ears with long earlobes, spiked teeth with protruding fangs from the lower jaw, and large heads with a marking. They are mostly nude aside from a loincloth and bands around their wrists and ankles. They typically wield spiked clubs as weapons. Goblin singers wear fur collar with fur wrist bands, have and additional marking on the abdomen, and wield horn which they use to generate a magical soundwave.
Hob Goblins (大亜人,,Hobugoburin) are a type of goblin. They resemble goblins but are larger, more obese and do not wield weapons.
Goblin Ogres (亜人鬼,,Goburin Ōga) are gigantic goblins, large enough to crush a human in the palm of their hands. They are giant humanoid creatures with four horns protruding from their head, spiked teeth with fangs protruding from the lower jaw, clawed hands and feet, long hair with a beard, and cross shaped pupils. They typically do not use weapons, relying on their enormous size and attacking with their fists. Goblin Ogres are considered major threats requiring large parties to defeat.
Demon Garden Mushroom
Demon Garden Mushrooms (魔苑茸,,Maentake) are mushroom-like lifeforms resembling large brains. They emit an unholy protection field, allowing them to be used as transport devices for the Demon King's army and send troops from one place to another. Growing one requires the sacrifice of many people who are pure of heart. Though usually the size of a tree, they can grow to be over the size of a large building. The seed resembles a small brain the size of a walnut. It will attach itself to the chest of a sacrifice and embed its vein-like roots into them. The shape and color it takes indicates the quality of the sacrifice.
Standard Demon Garden Mushroom
Demon Garden Mushroom grown from high-quality sacrifice
Delmantid (蟷螂亜人,,Derumanteisu) are demi-humans with mantis-like features. They have four mantis-like arms but normal human legs. Their heads are in the shape of a mantis with large bug eyes and antennas, but retain human lips, nose, ears and hair. They possess sharp senses, high speed and attack power, powerful enough to cut in half multiple armed guards in an instant.
Daemon Mosquitacles (D・テンタモス,,Daimon tentamosu) are creatures created by Dabada Dabaharl after being reborn as a demon. The resemble detatched tentacles with a single eye and veiny bug-like wings.
Dagrats (魔鼠,,Daguratsuto) are rodent-like creatures that can be found within the dungeon Minadonari. Individually they are weak and worth little EXP, but they are capable of posing a threat by swarming in large numbers. Dagrats resemble rats with visible fangs and larger tails, with markings on their head and back.
Curiovines (学者蔓,,Kiyuriobain) are tentacle creatures that can be found within the dungeon Minadonari. While they don't eat people, they do feed off their bodily fluids. They are capable of learning, improving their predations methods to strip clothes to better access bodily fluids. Harming them will cause them to call for reinforcements.