Susuwatari

Susuwatari (Japanese ススワタリ,煤渡り; "wandering soot"), also called Makkuro kurosuke (まっくろくろすけ; "makkuro" meaning "pitch black", and "～suke" being a common ending for boys names), is the name of a fictitious yōkai which was devised by Hayao Miyazaki, drawn by Studio Ghibli, known from the famous anime-productions My Neighbor Totoro and Spirited Away where, in the former, they are identified as "black soots" in early subtitles, as "dust bunnies" in the Streamline Pictures English dub, and as "soot sprites" or "gremlins" in the Walt Disney Studios English dubbed version.

Description
Susuwatari are described and shown as tennis ball-sized, pitch-black and fuzzy-haired beings with two large eyes and long, thin legs.

My Neighbor Totoro
In My Neighbor Totoro, the house the main characters move into is full of Susuwatari, which are rationalized as Makkuro Kurosuke, an optical illusion caused by moving quickly from light into darkness. Seeing that the family is composed of good people, the Susuwatari leave the house to move to another abandoned area.

Spirited Away
They later reappeared in Spirited Away as workers in Kamaji's boiler room. They are small, black as soot and appear fuzzy, with spherical bodies and two inquisitive eyes. They move by hovering around, but they can extend stick-like legs and arms from their bodies to do certain tasks, and can lift objects many times their own weight. They make a squeaky murmuring sound when excited, and dissolve into powder (soot) if crushed.

The protagonist Sen (Chihiro) befriends a number of them by helping them carry coal. Sen is told that if these Susuwatari aren't given a job to do, they turn back into soot. Another character, Lin, feeds the Susuwatari much like farmers feed chickens, throwing handfuls of the Japanese candy konpeitō onto the ground for them to eat. After Sen is accepted among the staff of the bathhouse, chiefly by Kamaji and Lin, the Susuwatari become almost admiring of her, and help her in their small ways.