This is an overview of the names and the etymology of Japanese weekdays and the days of the month.
The five planets are named after the five elements in traditional East Asian philosophy: Fire (Mars), Water (Mercury), Wood (Jupiter), Metal (Venus), and Earth (Saturn). The Chinese transliteration of the planetary system was soon brought to Japan by the Japanese monk Kobo Daishi (弘法大師). Diaries of the Japanese statesman Fujiwara no Michinaga (藤原道長) show the seven-day system in use during the Heian Period. It was kept in use for astrological purposes until its promotion to a Western-style calendar during the Meiji era.
English Weekday | Japanese Weekday | Meaning |
---|---|---|
Monday | 月曜日 getsuyōbi | The Day of the Moon, 月 (tsuki, the moon) |
Tuesday | 火曜日 kayōbi | The Day of Fire, 火 (ka, fire), refers to the planet Mars (火星 kasei) |
Wednesday | 水曜日 suiyōbi | The Day of Water, 水 (mizu, water), refers to the planet Mercury (水星 suisei) |
Thursday | 木曜日 mokuyōbi | The Day of Wood, 木 (ki, tree or wood), refers to the planet Jupiter (木星 mokusei) |
Friday | 金曜日 kinyōbi | The Day of Metal, 金 (kin, metal or gold), refers to the planet Venus (金星 kinsei) |
Saturday | 土曜日 doyōbi | The Day of Earth, 土 (do, earth or soil), refers to the planet Saturn (土星 dosei) |
Sunday | 日曜日 nichiyōbi | The Day of the Sun, 日 (hi, sun), refers to the Sun (also 太陽 taiyō) |
Days of the month
Until the 1870s, the Japanese used an adjusted lunar calendar based on the Chinese calendar and without weeks. The old Japanese calendar just counted the days of each month.1 | 一日 | tsuitachi ("ippi" is also in legal or business use) | 17 | 十七日 | jūshichinichi |
2 | 二日 | futsuka | 18 | 十八日 | jūhachinichi |
3 | 三日 | mikka | 19 | 十九日 | jūkunichi |
4 | 四日 | yokka | 20 | 二十日 | hatsuka |
5 | 五日 | itsuka | 21 | 二十一日 | nijūichinichi |
6 | 六日 | muika | 22 | 二十二日 | nijūninichi |
7 | 七日 | nanoka | 23 | 二十三日 | nijūsannichi |
8 | 八日 | yōka | 24 | 二十四日 | nijūyokka |
9 | 九日 | kokonoka | 25 | 二十五日 | nijūgonichi |
10 | 十日 | tōka | 26 | 二十六日 | nijūrokunichi |
11 | 十一日 | jūichinichi | 27 | 二十七日 | nijūshichinichi |
12 | 十二日 | jūninichi | 28 | 二十八日 | nijūhachinichi |
13 | 十三日 | jūsannichi | 29 | 二十九日 | nijūkunichi |
14 | 十四日 | jūyokka | 30 | 三十日 | sanjūnichi |
15 | 十五日 | jūgonichi | 31 | 三十一日 | sanjūichinichi |
16 | 十六日 | jūrokunichi |
Adoption of the Western calendar
With the introduction of the Western calendar, names for the seven days of the week were adopted as well. They were partly derived from the Latin system. The Romans used the names of the seven planets of classical astronomy and numbered the days, beginning with Sunday. The East Asian naming system of weekdays is quite similar the Latin system and is based on the "Seven Luminaries" (七曜 shichiyō), which consists of the Sun, Moon and the five planets visible to the naked eye.The five planets are named after the five elements in traditional East Asian philosophy: Fire (Mars), Water (Mercury), Wood (Jupiter), Metal (Venus), and Earth (Saturn). The Chinese transliteration of the planetary system was soon brought to Japan by the Japanese monk Kobo Daishi (弘法大師). Diaries of the Japanese statesman Fujiwara no Michinaga (藤原道長) show the seven-day system in use during the Heian Period. It was kept in use for astrological purposes until its promotion to a Western-style calendar during the Meiji era.