The days of the week in Japanese all end in youbi (曜日), "day of the week," attached to an element: getsuyoubi (月曜日) is Monday, kayoubi (火曜日) Tuesday, suiyoubi (水曜日) Wednesday, mokuyoubi (木曜日) Thursday, kinyoubi (金曜日) Friday, doyoubi (土曜日) Saturday, and nichiyoubi (日曜日) Sunday.
Each of those elements doubles as a celestial body, so the Japanese week is secretly a tour of the planets — the same ancient sky that named the English week, arriving from the opposite side of the world.
The seven days
The pattern never changes: element kanji plus youbi. Learn one and you have learned the shape of all seven.
| Day | Japanese | Romaji | Element / planet |
|---|---|---|---|
| Monday | 月曜日 | getsuyoubi | moon |
| Tuesday | 火曜日 | kayoubi | fire / Mars |
| Wednesday | 水曜日 | suiyoubi | water / Mercury |
| Thursday | 木曜日 | mokuyoubi | wood / Jupiter |
| Friday | 金曜日 | kinyoubi | gold / Venus |
| Saturday | 土曜日 | doyoubi | earth / Saturn |
| Sunday | 日曜日 | nichiyoubi | sun |
To say something happens on a given day, add ni (に): kinyoubi ni (金曜日に) means "on Friday." In casual speech people often drop the final syllable and say getsuyou or kayou, much like shortening "Monday" to "Mon."
Planets on both ends of the world
The overlap with English is not a coincidence. Both weeks descend from the seven "moving" lights of classical astrology — the sun, the moon, and the five planets visible to the naked eye.
English kept the Roman planet-gods where you can still see them (Saturday for Saturn, Sunday for the sun, Monday for the moon) and swapped the rest for Norse equivalents — Tuesday for the war god Tiw, standing in for Mars; Thursday for Thor, the thunderer, in place of Jupiter; Friday for the goddess Frigg, matched to Venus. Japan received the same seven-day scheme by way of China, pairing each planet with one of the five classical elements.
Look at the pairing and it lines up almost perfectly. Mars is the planet of fire, so Tuesday is kayoubi (火曜日), fire-day. Venus is the golden evening star, so Friday is kinyoubi (金曜日), gold-day. Two civilizations on opposite ends of Eurasia, reading the same handful of stars and reaching the same week.
Today, tomorrow, yesterday
In everyday life you will reach for relative-time words even more than the day names. These three are essential.
今日
kyou
today
明日
ashita
tomorrow
昨日
kinou
yesterday
The weekend is shuumatsu (週末), literally "week-end" — the days when trains fill with people heading for the mountains, the coast, and the hot springs. To place things by week, three more words come up constantly: konshuu (今週) this week, raishuu (来週) next week, and senshuu (先週) last week.
A head start on kanji
There is a quiet bonus buried in the day names. The seven element characters — 日 sun, 月 moon, 火 fire, 水 water, 木 wood, 金 gold, 土 earth — are among the very first kanji most learners meet, because they pull double duty as common standalone words.
So when you memorize the days of the week, you are also quietly learning seven high-frequency characters that show up everywhere from calendars to street signs.
Keep learning Japanese
Once the day names click, planning in Japanese — "see you Friday," "let's meet Sunday" — falls into place. Keep building your everyday vocabulary with our free essential Japanese phrases, and practice the readings with audio and spaced repetition in the Pretalk app until 月曜日 reads as "Monday" at a glance.
