The hitotsume-nyuudo is a monk youkai born from the dead soul of an ornery, whip-cracking head priest. The image is said to have originated from an ancient ritual where a priest would offer one of his eyes to the gods.
As for Backbeard (misspelling of "bugbear"), it's originally a major antagonist from GeGeGe no Kitaro, who possessed all the powers described here. One 2ch user captioned a picture of him with that infamous line, and since it was the golden age of gijinka, the birth of Beako followed suit.
One-eyed Monk
Monoeyes who have converted to buddhism.
Aside from being nuns, they're no different from standard monoeyes.
Perhaps because they are not troubled by the looks they receive, they are extremely serious and hard on themselves as well as others.
They use their eye to spot those who neglect their training.Cyclops
An usually large subspecies of monoeye with exceptional smithing abilities.
Their large eye allows them to accurately determine the temperature of fire and iron, which is the source of their unique smithing techniques.
Other monoeyes view their physical gifts (especially their breasts) with envy.Backbeard
A subspecies that possesses powerful eye abilities.
Their abilities allow them to hypnotize anyone who looks into their eye, blind others with their glittering eye, or even shoot laser beams from their eye.
In contrast with this great power, their bodies are small and childlike, and they are often treated like children, much to their dismay.
Because of this, they are very suspicious, and when anyone show them the slightest kindness, they shout, "You damn lolicon!" and run the other way.Monoeye SubspeciesMonoeye
A non-human species with a single large eye.
Standard monoeye subspecies.
Aside from their visual hyperacuity, they are not much different from ordinary humans.
Because they have only one eye, humans as well as other non-human species have an aversion to monoeyes, which is cause for concern among the entire species.
Having only one eye gives them trouble perceiving in three dimensions, and the size of their eye makes them susceptible to dry eye and allergies.
