Nukekubi

Nukekubi (抜首, written in Chinese characters, meaning Detachable Neck?, also written in Japanese Hiragana characters as "ぬけくび" or Japanese Katakana characters as "ヌケクビ" (But still read as "Nukekubi")) are monsters found in Japanese folklore. By day, nukekubi appear to be normal human beings. By night, however, their heads detach at the neck smoothly from their bodies and fly about independently in search of human prey. These heads attack by screaming (to increase their victims' fright), then closing in and biting.