The following month names, when used with the old-style Japanese calendar, don't correspond to the modern months, which are equivalent to January, February, etc., but to the old-style lunar calendar months.
| Japanese (rōmaji) | Japanese (kanji) | Numbered name | Notes |
|---|---|---|---|
| mutsuki | 睦月 | ichigatsu (一月) | Month of harmony |
| kisaragi | 如月 | nigatsu (ニ月) | Month of wearing extra layers of clothes |
| yayoi | 弥生 | sangatsu (三月) | Month of growth |
| uzuki | 卯月 | shigatsu (四月) | Month in which unohana (卯の花) blooms |
| satsuki | 早月, 皐月 | gogatsu (五月) | Month of planting rice sprouts |
| minazuki | 水無月 | rokugatsu (六月) | Month of no water |
| fumizuki, fuzuki | 文月 | shichigatsu (七月) | Month of letters |
| hazuki | 葉月 | hachigatsu (八月) | Month of leaves |
| nagatsuki | 長月 | kugatsu (九月) | Autumn long month |
| kannazuki, kaminazuki | 神無月 | jūgatsu (十月) | Month of no gods. Called kamiarizuki (神在月) in Izumo (Tottori prefecture) because the gods were said to gather there. |
| shimotsuki | 霜月 | jūichigatsu (十一月) | Month of frost |
| shiwasu | 師走 | jūnigatsu (十二月) | Month of busy priests |
The na (無) needs explanation.
From {{newsmsgscj|c952e14535034bc4|NAKANO Yasuaki}}: :It has been very popular in Japan to name the months by numbers. Months in the old calendar had their own names, such as Mutsuki, Kisaragi, etc., but these names appeared only in novels, poems or literary expressions. I think the official documents called months by numbers (in very ancient ages they might have been named using the Chinese zoological sequence).
| number | Japanese (rōmaji) | Japanese (kanji) | Notes |
|---|---|---|---|
| 1 | tsuitachi | 一日 | The beginning of the month. It comes from {{jr|tsuki (month, moon) + tatsu (to stand up) |
| 2 | futsuka | 二日 | |
| 3 | mikka | 三日 | |
| 4 | yokka | 四日 | |
| 5 | itsuka | 五日 | |
| 6 | muika | 六日 | |
| 7 | nanoka | 七日 | |
| 8 | yōka | 八日 | |
| 9 | kokonoka | 九日 | |
| 10 | tōka | 十日（とおか) | |
| 14 | jūyokka | 十四日 | |
| 20 | hatsuka | 二十日 | |
| 24 | nijūyokka | 二十四日 |