also: ごまのはえ
thief posing as a fellow traveler
Historical term for a thief who pretends to be a travel companion in order to steal. The kanji 護摩の灰 literally means 'ashes of a goma fire ritual', while 胡麻の蝿 means 'sesame fly'; both are ateji-like spellings for the reading.
At Edo-period inns, people were warned to be careful of thieves posing as fellow travelers.
Standard kanji spelling for this historical term.
Alternate spelling with the reading ごまのはえ, using 胡麻 (sesame) and 蝿 (fly). Rare and possibly ateji.
The origin is uncertain. The spelling 護摩の灰 (goma no hai, 'ashes of a goma fire ritual') is likely ateji, while 胡麻の蝿 (goma no hae, 'sesame fly') may be a phonetic rendering. The term is historical and rarely used in modern Japanese.