Olgoi Khorkoi (オルゴイコルイ, Orugoikorukoi) is a demon in the series.
History
he Mongolian death worm (Mongolian: олгой-хорхой, olgoi-khorkhoi, "large intestine worm") is a creature purported to exist in the Gobi Desert. It is generally considered a cryptozoological creature (cryptid): one whose sightings and reports are disputed or unconfirmed. The worm is the subject of a number of extraordinary claims by Mongolian locals - such as the ability of the worm to spew forth sulfuric acid that, on contact, will turn anything it touches yellow and corroded (and which would kill a human), as well as its purported ability to kill at a distance by means of electric discharge.