Yamajijii (山爺) or Yamachichi (山父) (or, depending on area, "yamanjii") is a type of yōkai told about in Japan.
It is said to be a yōkai that takes on the appearance of an old man with one eye and one leg. According to the publication by the Tosa Folkloristics Department, the "Early Modern Tosa Yōkai Documentation (近世土佐妖怪資料 Kinsei Tosa Yōkai Shiryou)," with the Kōchi Prefecture being the first, it was passed down in Shikoku, and with a height of about 3-4 shaku (about 90-120 centimeters), and there is gray hair growing all over its body, and although it has two eyes, since one of them is large and the other is unusually small, it is seen as having just one eye. It is said that the legend where it has one eye is a misunderstanding of these two eyes that were seen as one eye and then passed down. Since it has teeth that have a hardness that could easily crush the bones of wild boar or a monkey etc., hunters would tame this yamajijii with bait, and use it to drive away wolves.
It would appear on roads where humans come and go, but they don't appear before people, but rather leave round footprints about 6 or 7 shaku apart that are about 4 shaku wide that are as if a mallet pressed into it.
Worthy of special mention is its extravagantly large voice, and its should voice would echo around the mountains, shake the sky and earth, make leaves fall, and make the nearby trees and rocks move. It is said that there are some who have had their eardrums torn by this great voice and died. The yamajijii would sometimes engage in contests of seeing who has the larger voice, and a folktale where a hunter attempted to show his voice by making a gunshot to defeat yamajijii in this contest. However, yamajijii, who notice that he was deceived through a gunshot, shapeshifted into a spider and sneaked into the opponent's home, and attacked his sleep, in order to clear his resentment. Also, when the hunter prepared for the contest of comparing the loudness of voices, and on the evening of New Year's Eve, while praying at the Ise Hachiman Daibosatsu, he etched in the name "Ise Hachiman Daibosatsu" on a bullet that he made, which he carried around with him regularly. It is said that this bullet was something that a hunter in the past always carried with him, and always hit even without aiming, but by carrying it around one would certainly encounter something strange like a yōkai, and against a yamajijii, by making a threat by saying that one would fire this bullet, the yamajijii would shudder and fear and run away.