A Nekomata in Japanese folklore is a cat with supernatural abilities akin to those of the fox or raccoon dog.
A cat may become a Bakeneko in a number of ways: it may reach a certain age, be kept for a certain number of years, grow to a certain size, or be allowed to keep a long tail. In the last case, the tail forks in two and the bakeneko is then called a nekomata. This superstition may have some connection to the breeding of the Japanese Bobtail.
A bakeneko will haunt any household it is kept in, creating ghostly fireballs, menacing sleepers, walking on its hind legs, changing its shape into that of a human, and even devouring its own mistress in order to shapeshift and take her place. When it is finally killed, its body may be as much as five feet in length.
It also poses a danger if allowed into a room with a fresh corpse; a cat is believed to be capable of reanimating a body by jumping over it.