"Going for walks at night as a hobby, this Oni Yo-kai sometimes even goes for a walk as nothing but a head. They hate being seen by humans, and since they take the eyeballs of those that see them, lay down on the ground if you happen to encounter them."
Yagyou is a fair-sized humanoid Yo-kai with clay-colored skin, a visible pointy ear and a sole visible sharp teal right eye, with the left one covered by an eye-patch. He has magenta-colored hair with two black horns sticking out, and a cloudy-looking scarf, teal in color. he wears a samurai-like attire with long clay-brown sleeves and a darker brown-colored layer of clothing above, a yellow sash on his waist, as well as two-teeth geta sandals with white tabi. he carries a fairly big golden curved sword with a green handle.
It is also worth noting that Yagyou's head can freely detach from his body.
Bounces some of the damage taken back to the enemy.
Yagyou is based on Yagyou-san (Japanese: 夜行さん,Yagyō-san, "the night wanderer"), a one-eyed youkai resembling an oni that hails from the Tokushima prefecture. He appears on a headless horse on the night before Setsubun or the last day of the year, riding down the most beaten paths. Those who encounter him on these nights risk getting bodily thrown aside or kicked by his steed. To avoid this, one should put their zōri on their head and kneel down begging for forgiveness. Some sources say Yagyou-san's steed is a youkai of its own, related to folk tales of disembodied horse parts hanging from trees, like the sagari ("dangler") or the uma no ashi ("horse legs").
Yagyou's ability to remove his head freely, however, references an altogether different youkai, the Nukekubi (Japanese: ぬけ首,Nukekubi), the original type of Rokurokubi (Lady Longnek#Origin), where instead of their necks stretching, their heads become disembodied at night and float away from the body. Nukekubi have been noted, though not a common event, to attack passerby and drink blood. Sometimes, however, Nukekubi can be used to describe out-of-body events, such as a story featuring a female nukekubi being chased by a man with a sword all the way home, where the woman woke up and recalled the chase as a nightmare.
In Yo-kai Watch 3, during the first "ENMA NOTE" quest, Yagyo, alongside a group of rebel yo-kai, attempt to kill Lord Enma with the use of the Enma Note, this is clearly a parody to the acclaimed series Death Note. Notice that the 3 yo-kai involved all make a reference to the protagonist of said series (Yagyo having the power to see a yo-kai's true name with his evil eye, Inugami standing as the Shinigami, and Kirameki porting "Kira" in his name, which is a term used to refer to those who use the death note).