Cryptids: Boroboroton

 

Boroboroton as depicted in Toriyama Sekien's Hyakki Tsurezure Bukuro

The Boroboroton belongs is a specific kind of Japanese Yokai called Tsukumogami or artifact spirit. These kinds of spirits are from manmade objects either possessed by ghosts or spirits or they form their own spirit from constant use for at least 90 to 100 years. If They form their own spirit they often look brand new or pristine despite their old age.

The Boroboroton is a tattered futon or a Japanese sleeping mat. They come alive at night and will come to life at night especially if it feels ignored or needless. In revenge, they will rise up in the air and kill any sleeping person they make contact with. It will wrap around the head and neck of the sleeper with the intent of strangling them to death. 

Sometimes they will meet with other Tsukumogami and throw noisy parties or leave the gome search for other beings. 

SOURCES:

Wikipedia

Yokai Wiki