7th, 7th calendar sign
庚 centers on the seventh position in the traditional calendar cycle, specifically the 7th celestial stem. Its meaning is primarily ordinal and calendrical.
庚 is an ancient character whose original pictographic meaning is uncertain. It was adopted early as the seventh of the ten celestial stems (十干) in the Chinese calendar system.
The outer 广 looks like a building, and inside is a shape like a hand holding a pestle. Imagine the seventh worker in a row pounding grain under the roof: 庚 is the 7th sign.
For コウ, picture a calendar page with the 7th sign circled, and a coach (コウ) pointing at it, saying 'This is the seventh day.' Coach -> コウ.
7th in rank; seventh sign of the Chinese calendar
Metal Monkey (57th term of the sexagenary cycle, e.g. 1920, 1980, 2040)
same age
Metal Horse (7th term of the sexagenary cycle, e.g. 1930, 1990, 2050)
Kōgo register; Japan's first census register (670)
Metal Rat (37th term of the sexagenary cycle, e.g. 1960, 2020, 2080)
Metal Tiger (27th term of the sexagenary cycle, e.g. 1950, 2010, 2070)
Metal Dog (47th term of the sexagenary cycle, e.g. 1910, 1970, 2030)
roadside standing stone dedicated to the Buddhist deity Shōmen Kongō (usu. also engraved with the three wise monkeys)
kōshin-machi; staying awake on the eve of the 57th day of the sexagenary cycle to prevent the three worms that were said to inhabit the human gut from reporting one's wrongdoings to the gods; a tradition that began among nobility in the Heian period and became widespread during the Edo period
Metal Monkey month; lunar month that contains a day of the Metal Monkey (essentially every other month) during which it was believed colds were more frequent
Pinguicula ramosa (butterwort species)
China rose (Rosa chinensis); monthly rosebush
kōshin-machi association
Metal Dragon (17th term of the sexagenary cycle, e.g. 1940, 2000, 2060)