The number “one” is “いち ichi” in Japanese but there are many ways of counting “one” in Japanese, depending on the object that you are attaching the number to.
These are called “counters” and they are required to count different types of objects, animals, or people.
Counters are not interchangeable. For example, you must use the “flat-item” counter to count paper and the “people” counter to count people and not vice versa.
In this article, we are going to look at some widely used counters to count one.
1. 一人(ひとり) Hitori
The counter for person is 人 nin but one person is not ichinin. If you want to say “one person”, the word is hitori.
If a waiter asks how many of you while you are entering the restaurant, you can say hitori desu.
2. 一(ひと)つ Hitotsu
“~ tsu” is a counter to count any generic item that has a rare or no counter. Hitotsu is used when you are counting one item.
If you want to order one item from a menu, you can say “一つお願(ねが)いします。Hitotsu onegaishimasu.” Onegaishimasu is “please”.
3. 一本(いっぽん) Ippon
“~pon / hon / bon” (there is a change in pronunciation depending on the prefix number) is used to count long and cylindrical objects such as bottles, pencils, bananas, chopsticks, and umbrellas.
If you are ordering a bottle of beer at a restaurant, you can say “ビール一本お願いします Biiru ippon onegaishimasu”.
4. 一冊(いっさつ) Issatsu
“~ satsu” is used to count books, volumes, magazines, or other bound objects. Issatsu refers to one copy.
5. 一枚(いちまい) Ichimai
“~ mai” is used to count thin and flat things such as paper, CDs, stamps, T-shirts, towels, and blankets.
6. 一匹(いっぴき) Ippiki
One (small) animal
“~ piki / hiki / biki” (again, there is a change in pronunciation depending on the prefix number) is used to count small animals such as cats and dogs.
The emphasis is on small animals, because big animals like elephants and horses use the counter 頭 too. If you have a cat at home, you can say 猫(ねこ)が一匹(いっぴき)います。Neko ga ippiki imasu.
As you have seen from the above, counting one is not an easy matter in Japanese.
You have to use the correct counter for the object that you are referring to, and sometimes, the pronunciation changes according to the prefix number as well.
I hope this article is useful to you for a start.