Not much is known about Nobusuma, other than that they resemble the Japanese giant flying squirrels.
While Kitarō and the others speculate on which Japanese yōkai is causing the recent vampiric incidents, Mana mentions the Nobusuma as a possibility. However she reads that the one captured by a man named Ihei long ago only drank cat blood.
Blood Draining: They are capable of consuming the blood of their victims, with one in particular favoring cat blood.
The Nobusuma were originally bats which lived to a very old age and developed magical powers. They look almost identical to the musasabi, or Japanese giant flying squirrels, but are much more dangerous. Their diet consists of nuts, fruit, and berries, but they also feed on fire, and by sucking blood from humans and small animals, cats being an example. They attack travelers at night by swooping down from the trees and onto the faces of their victims. There they latch on and begin to suck their blood. They also swoop down and blow out torches and lanterns, flying back up into the night sky crying “gaa gaa!” when they do not need to feed.