The names of the days come from the five visible planets, which in turn are named after the five Chinese elements (metal, wood, water, fire, earth), and from the moon and sun (yin and yang).
On the origin of the names of the days of the week, also see East Asian Seven Luminaries. These holidays have no religious meaning (except those who believe in Christianity or Judaism).
These month names also appear from time to time on jidaigeki, contemporary television shows and movies set in the Edo period or earlier.
In this name the na is actually a possessive particle, so Kaminazuki means "Month of the Gods", not "Month without Gods" (Kaminakizuki), similarly to Minatsuki, the "Month of Water".Beginning with Meiji (1868–1912), each reign has been one era, but many earlier Emperors decreed a new era upon any major event; the last pre-Meiji Emperor's reign (1846–1867) was split into seven eras, one of which lasted only one year.The nengō system remains in wide use, especially on official documents and government forms.The imperial year system (kōki) was used from 1872 to the Second World War.Imperial year 1 (Kōki 1) was the year when the legendary Emperor Jimmu founded Japan – 660 BC according to the Gregorian Calendar.The seven-day week, with names for the days corresponding to the Latin system, was brought to Japan around AD 800 with the Buddhist calendar.