Furuōgi - 古扇 (ふるおうぎ) - "old folding fan."
• About this yokai: A fat, blue, teal or green, goblin-esc monster with a huge worn out folding fan lodged in the back of its head: a regular attendant in the Night Parade of 100 Demons, often seen walking among other Tsukumogami, without proper context or explanation. - So, Speculative theories abound with this one: I've read in some books that it might actually be a dragon, boar, or a rabbit that was perhaps pictured on the fan itself; the fan was left abandoned in a field and faded over time & so the fan itself then became a Tsukumogami. – Folding fans are also a staple of classic slapstick comedy. (in which case they're known as Harisen 張り扇 or "slapping fans") - Im unsure how far back the trope of slapping someone upside the head with a fan goes, but perhaps its just a silly yokai down that vein? - Did someone slap him so hard that it got stuck? who knows... Your guess is as good as mine!
•History: As said initially, ultimately, Its a nameless yokai, featured in most of the earliest Hyakki Yagyo Emaki picture scrolls, the old scrolls have no explanation, story or names for any of the yokai included, so its true context is a mystery, probably popular knowledge at one point, but now lost to history. He's running along next to a yokai 'Nyoi-staff' (often used as a back-scratcher) and chasing after a yokai hiding under a black sheet, often behind them is a green tengu like monster holding a fancy buddhist staff, perhaps he has some religious context? its hard to say!
['Furuogi' from 百鬼夜行絵巻 (hyakki yagyo: the night parade of 100 demons.)]
Yokai art sticker by @Samkalensky part of my night parade of 100 demons sticker collection! check my shop & follow for many more!!