Uzudoll - 渦人形 - "Uzu Ningyo" [Urban Legend/Cursed doll] - 'Vortex Doll.'
• About this Doll: An eerie child-sized doll with a bobbed haircut, white face, hollow, pitch-back eyes, a smile shaped like a crescent moon. it has an abnormally thin, extendable neck which can reach up to a meter. it wears a faded old kimono & sits with its hands on its knees, legs tucked neatly underneath. The doll was made in Kanpo II, 1743. -it lets out a toneless, robotic laugh; "Hyo. hyo. hyo." – Causing insanity in those that hear it, they are unable to stop laughing, crying & speaking gibberish. ...Even if you burn it... it will eventually return.
• Story summary: When the original poster was a sophomore in high school, they visited a remote club training camp, deep in the mountains. (they don't give an exact location.) During a trip to a nearby convenience store, he and a group of his classmates noticed something peeking out of an old cabin's front door. Naturally, the group becomes curious and that night they go to check it out as 'a test of courage' ... [Note: you can listen to the full story, expertly translated by Tara on Kowabana.]
• History: The story originates from posts dating to May 19th, 2011 on the 2chan message boards, of course, it was presented as a 'true' story reported on by the Anonymous Original Poster & as a first-person account. [Like many #chan posts, if it actually happened or not is up in the air. - (probably not.) - Regardless, its highly regarded as one of 2chans best 'creepy pasta' posts, among the likes of Hasshakusama, Kunekune, The Kotoribako & others.] - Regardless of the validity of the story, over the years, The uzu doll has been included in quite a few modern urban legend encyclopedias & even horror games.
• Similar yokai: During the story, the monks mistake the doll for the yokai known as Hyosube. (Here called "ひょうせ" "Hyosei") Who's infectious laugh also causes madness.) - The dolls long neck also gives it an appearance similar to the yokai known as Rokurokubi, it should probably not be confused with the famous Okiku doll, these yokai likely served as inspiration for the story.