 One notorious tengu from the 12th century was himself the ghost of an emperor . The Hōgen Monogatari tells the story of Emperor <unk> , who was forced by his father to abandon the throne . When he later raised the Hōgen Rebellion to take back the country from Emperor Go @-@ Shirakawa , he was defeated and exiled to <unk> Province on Shikoku . According to legend he died in torment , having sworn to haunt the nation of Japan as a great demon , and thus became a fearsome tengu with long nails and eyes like a kite 's . 
