1. Where Zoni Came From: Offering Food Turned Everyday Meal
The earliest written record of zoni is found in a cookbook from 1497 called "Yamanouchi Ryorisho". [1] According to folk scholar Yanagita Kunio, the dish likely began as an offering to the New Year god (Toshigami-sama). After the gods were served the mochi, people would eat it together. [1]
2. Square or Round? How Mochi Shape Divides Eastern and Western Japan
The shape of the mochi used in zoni changes depending on where you are in Japan. Generally, eastern Japan uses "kaku-mochi" (square mochi), while western Japan uses "maru-mochi" (round mochi). [2]
The dividing line between these two styles runs roughly along a line connecting Niigata Prefecture and Shizuoka Prefecture. [2] However, this is not a strict rule that changes instantly as you cross it; there are exceptions in various regions.
3. Why Eastern Japan Uses Square Mochi: The Story of Edo (Tokyo)
In Edo, which is modern-day Tokyo, the population was growing rapidly. Mochi shops needed to produce large amounts of mochi quickly for these new residents. They developed a method where they stretched the mochi thin and cut it into squares with a knife. [3] This was faster and more efficient than shaping each piece by hand into a round ball.
Additionally, there was a cultural reason for preferring square mochi among the samurai class. The act of stretching the mochi ("nosu") sounded like the phrase "to defeat enemies" ("teki wo nosu"). [3] For warriors, this wordplay made square mochi welcomed as good luck.
4. Why Western Japan Uses Round Mochi: Avoiding Mold in Warm Weather
In warmer western Japan, square mochi had a practical disadvantage: the cut edges were prone to growing mold. [4] One theory suggests that round mochi, which has no cut surfaces, was more resistant to mold than square mochi. This is similar to how fruit with bruises rots faster than unbruised fruit, though mochi is not fruit.
However, this factor alone does not explain everything. There are exceptions where regions do not follow the east-west rule. For example, Yamagata Prefecture and Kochi Prefecture use round mochi despite their locations. [4]
5. Clear Soy Sauce Broth or White Miso Broth in Zoni
The broth itself also varies significantly by region. In many parts of Japan, the soup is "sumashi-jiru," a clear broth flavored with soy sauce. [5]
However, in the Kansai region, particularly around Osaka, the traditional broth is made with white miso and has a sweeter taste. [5]
6. Local Zoni Ingredients Found Only in Certain Regions
Some regions have very specific local versions of zoni that use ingredients unique to their area. In Kagawa Prefecture, there is a sweet version of zoni where white miso soup contains round mochi filled with red bean paste (anko). [6]
In Niigata Prefecture, some places add salmon or salmon roe to their soup. [6] In Hakata, Fukuoka Prefecture, the local zoni uses a dashi (broth) made from "ago" fish and includes yellowtail and katsuona. [6]
Using what is locally available in each region is what has created these differences in zoni.
7. How to Investigate Your Own Family's Zoni
Next New Year, you can investigate your own family’s zoni. Check if the broth is soy sauce-based or white miso-based, and whether the mochi is square or round.
Compare your findings with the general rule that "East is square, West is round." If your family’s traditions do not fit this pattern, that is also an interesting discovery about your own local history and heritage.