1. How Old Is a Baby Born in December Under Kazoe-doshi?
In the kazoe-doshi system, the year you are born counts as 1 year old. After that, you add 1 year each time a new year begins [1]. For example, a baby born on December 20 is 1 year old at birth. Just 12 days later, on January 1, that baby is already 2 years old. By the way we usually count age today, this baby is still 0 years old. The same child can be called "0 years old" or "2 years old" depending on the counting method used. So, what is the age we usually use now?
2. How Is Counting Age by Birthday (Man-nen-rei) Different from Kazoe-doshi?
The current standard, called man-nen-rei, starts at 0 years old on the day of birth. You add 1 year each time you have a birthday [1]. Japan's legal age is based on this method, established by a law from 1902 (Meiji 35). The law from 1949 also uses this as the standard [2]. The big difference between the two methods is when the age increases. In kazoe-doshi, everyone gets older on the same day: New Year's Day. In man-nen-rei, birthdays are different for each person, so the day the age increases varies from person to person. Why did kazoe-doshi start counting from 1 year old at birth?
3. Why Did Kazoe-doshi Count Babies as 1 Year Old at Birth?
The exact reason for counting birth as 1 year old is not clear. There are two common explanations [5]. One theory says that the time spent in the mother's womb is counted as 0 years, so the baby has already lived for 1 year by the time it is born. The other theory comes from the idea that people receive a new age from the New Year's deity on New Year's Day, so everyone ages on that day. However, neither of these is an academically proven origin. These are explanations people have suggested, but neither has been proven. Perhaps the idea that life begins before birth is what is built into kazoe-doshi. In 1949, the government asked people to try to stop using this way of counting. What was the problem?
4. What Did Parliament Worry About in 1949 When Discussing Age Counting?
On May 12, 1949, at the House of Councillors plenary session, Tanaka Kōtarō, the chair of the Education Committee, explained the reason for the bill. It proposed stopping age calculations based on kazoe-doshi and changing to man-nen-rei based on the 1902 law [3]. Three main reasons were given. First, kazoe-doshi does not show the actual age correctly. Second, food rationing at the time required strict calorie calculations based on age, and kazoe-doshi did not fit these calculations. Third, foreign countries and international statistics use man-nen-rei, so using a different system caused problems for international exchange [3]. Post-war life and relations with other countries were reasons to unify the counting method. Did this law ban kazoe-doshi?
5. Did the 1949 Age Law Tell People to Stop Using Kazoe-doshi or Just to Try?
The "Law Concerning the Method of Counting Age" (Law No. 96 of 1949) was published on May 24, 1949, and enforced on January 1, 1950 [2]. It asks citizens to try to change the custom of stating age in kazoe-doshi. The law asks people to try to change this custom rather than banning it. When government agencies state age, they must use years or months. If they must use kazoe-doshi, they must state that clearly [2]. The government was also asked to make the law's intent known. Because the law only asked people to "try" to change and asked the government to inform people, kazoe-doshi remained in daily life. The most well-known example is yakudoshi.
6. Where Is Kazoe-doshi Still Used Today, Such as for Yakudoshi?
Yakudoshi (unlucky years) is usually counted using kazoe-doshi. Commonly cited ages include 19, 33, and 37 for women, and 25, 42, and 61 for men. People are told to be careful during the three years of the previous year, the year itself, and the following year [4]. At shrines and temples, people still receive prayers to ward off bad luck. Using this counting method, if you have passed New Year's Day but not your birthday, your kazoe-doshi is your current age plus 2. If you have passed your birthday, it is your current age plus 1. The ages and counting methods for yakudoshi can vary by shrine, temple, or region. Even though the law asked people to change, ways of counting linked to life milestones did not disappear. Kazoe-doshi is a way of counting where everyone adds a year on New Year's Day.
7. How Can You Calculate Your Own Kazoe-doshi Age?
Let's calculate your own kazoe-doshi using your current age in man-nen-rei. If you have passed your birthday, add 1 to your current age. If you are between New Year's Day and the day before your birthday, add 2 to your current age. How old will you be in kazoe-doshi on New Year's Day next year? Another idea: ask your family, "Have you ever been told your age in kazoe-doshi?" They might remember events like Shichi-Go-San (a children's festival) or yakudoshi where this counting method is used. In the National Diet Minutes Search System, you can read the original text of the speech from the House of Councillors plenary session on May 12, 1949 [3]. Try reading how the reasons were explained in their own words.