 In the 18th and 19th centuries , tengu came to be feared as the vigilant protectors of certain forests . In the 1764 collection of strange stories <unk> <unk> ( <unk> ) , a tale tells of a man who wanders into a deep valley while gathering leaves , only to be faced with a sudden and ferocious hailstorm . A group of peasants later tell him that he was in the valley where the <unk> live , and anyone who takes a single leaf from that place will surely die . In the <unk> Chomon Kishū ( <unk> ) , written in 1849 , the author describes the customs of the wood @-@ cutters of Mino Province , who used a sort of rice cake called <unk> @-@ mochi to placate the tengu , who would otherwise perpetrate all sorts of mischief . In other provinces a special kind of fish called <unk> was offered to the tengu by woodsmen and hunters , in exchange for a successful day 's work . The people of Ishikawa Prefecture have until recently believed that the tengu loathe mackerel , and have used this fish as a charm against kidnappings and hauntings by the mischievous spirits . 
