In his book "Myths and Legends of Japan", F. Halland Davis includes an old Japanese legend which he titles “The Vampire Cat.”
This legend begins with the Prince of Hizen enjoying the evening hours with his favorite consort, O Toyo. They do not notice that a cat has been following them. After O Toyo retires to her room and falls asleep, the cat, now gigantic, attacks her and strangles her.The cat then drags her body into the country side, buries it., and then takes her form. The prince of course knew nothing about the death of O Toyo and so he loved the false O Toyo. But then he fell ill and began to whither away.He had nightmares while he slept. It was suspected that he was prey to some demonic being while he slept. His courtiers sat in his room at night and tried to stay awake to protect him. But they always nodded off before morning. But then it came to pass that a loyal subject and faithful Buddhist named Ito Soda volunteered to take part in the vigil.After everyone else fell asleep, Ito Soda saw what appeared to be O Toyo enter the room through a sliding window. This figure smilingly approached the sleeping prince. But when the false O Toyo realized that Ito Soda was watching her, she left the room.The same thing happened on following nights until the form of O Toyo failed to appear. After that, the fake O Toyo lost interest in the prince and even neglected him while he was awake. Next, Ito Soda entered O Toyo’s room and presented the evidence he’d collected to the false O Toyo. The false O’Toyo then attacked him with a halberd (a pike with a battle-axe near the tip).When Ito Sota fended her off, she changed back into cat form and escaped. This same vampire cat then began troubling people living in the mountains. Finally, this vampire cat was killed in a hunt ordered by the prince. The prince recovered and Ito Soda received all the honors and awards he deserved.