Mamono ('''魔物''') is a [[Languages|Youkai-go]] term which means "evil spirit". It is a category of creatures that have appeared in the Mazes alongside [[youkai]], which possess a range of magical abilities and traits. Whereas youkai are sapient, civilized creatures that have integrated into society and communities, mamono are feral monsters residing in the Uncivilized Area, being one more category of dangerous creatures that can be found there.
Amanojaku is a Youkai-go term which can be translated to "heavenly evil spirit", though this is not a fair or accurate translation. Broken down separately, the word is composed of three or four characters: '''天''' (ama, meaning heavens, sky, or imperial), '''の''' (no, a possessive particle, omitted from the three-character reading), '''邪''' (ja, meaning wrong or wicked), and '''鬼''' (ku). This last character is the same character as the one used when writing [[oni]] in Youkai-go. A more accurate transliteration translation is "heavenly wicked oni".
Amanojaku are essentially a wicked version of [[oni]]. They very closely resemble regular oni, with the most notable differences being their eyes (flat black and lacking pupils and irises) and their horns (much shorter and nubbier than an oni's). However, amanojaku cannot speak or understand any kind of recognizable [[languages|language]] and are about as feral as any wild creature found in the Mazes. They seem to be semi-solitary, forming small groups and tribes in the Uncivilized Area. An amanojaku will typically barely tolerate members of its own species and react with violence towards anything else. Most importantly, they seem to have the ability to distinguish themselves from oni, suggesting that they may very well be self-aware.