My sensei told that is because nanaji seems like hanaji. Hanaji can meaning nose secretion. So that is the story i know, hope that can help you. Keep learning, Japanese is very cool.
It’s the other way around, actually.
On-yomi counting is,
ichi ni san shi go roku shichi hachi kyuu jyuu
kun-yomi counting is
hitotsu futatsu mitsu yotsu itsutsu muttsu nanatsu yattsu kokonotsu too
However, for some decades now it has been preferred to take ‘yon’ for 4 and ‘nana’ for 7 from kun-yomi counting and use them in on-yomi counting. The are various theories about superstitious reasons, but it seems the most likely reason is just that having ichi, shi, and shichi in the same counting system is liable to cause confusion, especially on a bad audio connection.
Some fixed terms like 七時、四月、七月 never made the switch and stand out in contrast to the majority of counting. You also might hear the old way of counting from old or old-fashioned people, or in very traditional settings, or in old movies.
shichiji and shichigatsu (july) are guaranteed. in other circumstances it’s sort of variable, i think 7人 can be either shichinin or nananin for example, but in most places nana is more likely. Can’t remember other guaranteed places to find shichi off the top of my head but i’m sure they exist.
shichi is the chinese loanword form of the numbers, and fits into the sino-japanese numeral system – ichi ni san shi go roku shichi hachi ku juu. 4 (shi) is replaced with yon because shi sounds like “death”, and 7 is replaced with nana because shichi sounds like ichi (and death?). Both of these are from the japonic numeral system – hito futa mi yon itsu mu nana ya kokono too – you’ll find this one usually for the object counting set or the days of the month. 9 (ku) is also usually replaced with kyuu which is an alternative sino reading of the kanji or something – because ku means suffering.
You’ll find that ku and shi for 9 and 4 have a similar distribution to shichi, but 4 is more often yon or yo-. So for time you get shichiji and kuji (but yoji); months you have shigatsu, shichigatsu, kugatsu; for people you have only yonin for 4 (shinin means corpse), but you can choose nananin/shichinin for 7, and kyuunin/kunin for 9.
So the answer to “why” is a bit of taboo avoidance, and a bit of just making 7 sound distinct from 1. And the reason it reverts to shichi in these cases is because they’re highly fixed phrases. You can think of the months as having “names” if it helps.
3 comments
My sensei told that is because nanaji seems like hanaji. Hanaji can meaning nose secretion. So that is the story i know, hope that can help you. Keep learning, Japanese is very cool.
It’s the other way around, actually.
On-yomi counting is,
ichi ni san shi go roku shichi hachi kyuu jyuu
kun-yomi counting is
hitotsu futatsu mitsu yotsu itsutsu muttsu nanatsu yattsu kokonotsu too
However, for some decades now it has been preferred to take ‘yon’ for 4 and ‘nana’ for 7 from kun-yomi counting and use them in on-yomi counting. The are various theories about superstitious reasons, but it seems the most likely reason is just that having ichi, shi, and shichi in the same counting system is liable to cause confusion, especially on a bad audio connection.
Some fixed terms like 七時、四月、七月 never made the switch and stand out in contrast to the majority of counting. You also might hear the old way of counting from old or old-fashioned people, or in very traditional settings, or in old movies.
shichiji and shichigatsu (july) are guaranteed. in other circumstances it’s sort of variable, i think 7人 can be either shichinin or nananin for example, but in most places nana is more likely. Can’t remember other guaranteed places to find shichi off the top of my head but i’m sure they exist.
shichi is the chinese loanword form of the numbers, and fits into the sino-japanese numeral system – ichi ni san shi go roku shichi hachi ku juu. 4 (shi) is replaced with yon because shi sounds like “death”, and 7 is replaced with nana because shichi sounds like ichi (and death?). Both of these are from the japonic numeral system – hito futa mi yon itsu mu nana ya kokono too – you’ll find this one usually for the object counting set or the days of the month. 9 (ku) is also usually replaced with kyuu which is an alternative sino reading of the kanji or something – because ku means suffering.
You’ll find that ku and shi for 9 and 4 have a similar distribution to shichi, but 4 is more often yon or yo-. So for time you get shichiji and kuji (but yoji); months you have shigatsu, shichigatsu, kugatsu; for people you have only yonin for 4 (shinin means corpse), but you can choose nananin/shichinin for 7, and kyuunin/kunin for 9.
So the answer to “why” is a bit of taboo avoidance, and a bit of just making 7 sound distinct from 1. And the reason it reverts to shichi in these cases is because they’re highly fixed phrases. You can think of the months as having “names” if it helps.