Over the years I’ve written several articles on a new year-related celebration called Kagami Biraki, which takes place on the 11th of January. Possibly the most iconic component of this is the kagami mochi (鏡餅), which is a rice cake made of a type of sticky rice that can be eaten. It is designed as 2-tier (either in one mold, or two separate pieces), and is often decorated in a beautiful manner. There is also a segment where a mallet is used to divide it by “breaking” the top surface, which means opening it to release the blessings kept inside by the toshigami (歳神), a deity that comes to visit one’s residence at the start of the new year to bring good fortune. Although this is a widely-known tradition, having kagami mochi isn’t practiced widely throughout Japan today due to modernization, although some families, or certain organizations for specific events, still keep this tradition going on.

As with most things in Japanese culture, there are plenty of symbolic meanings behind the kagami mochi and its appearance. For this article, the back story behind kagami mochi will be covered. We’ll look into the traditional practices regarding its shape, the superstitions behind the types of decorations used, as well as its relations to the mallet instead of a sharp instrument.
MEANING BEHIND SHAPE
The accepted practice for kagami mochi is to make it circular. This is obvious when this rice cake is looked at from above. There is one prime reason behind the circular shape, one that pays homage to ancient beliefs and practices.

Centuries ago, mirrors were made in a circle shape out of bronze. Going as far back as the Yayoi period (before 300 BC ~ 300 AD), these were valuable objects where only those of prestigious status could obtain one. From that time forward a strong belief regarding how mirrors can grant eternal life, or deliver good fortune to one’s descendants was attached to mirrors, giving it an auspicious nature. Also, shintō belief added to this with the idea that mirrors were like a gateway to different gods that were worshiped, such as the sun goddess Amenoho Akari no Miko (天火明命)¹.
Today, much of that ancient practice has been carried to present day, and influences the practice of Kagami Biraki. This gives us a clue as to the ancient bronze mirror being the reason for kagami mochi being circular, as well as a means to receive blessing from the toshigami for a long life.
WHY 2-TIER?
One of the more interesting features of the Kagami mochi is that it’s made as a 2-tier rice cake. While it may seem unusual, especially for something that should be more recognizable as, say a mirror. However, this 2-tier structure is symbolic, with reasoning behind it. Below are a few acceptable theories regarding this:

- Having the kagami mochi as 2-tier is believed to reinforce the blessing one receives, to ensure good fortune, and longevity for one’s life.
- Having a 2-tier design is a representation of the phrase fūfu wagō (夫婦和合). This phrase stands for happy union between marriage couples, and can be viewed as following the philosophy of inyō (陰陽, ying yang). The layers of the kagami mochi represent this union, and is important for those who are married.
- Under Shintō and Buddhism practices, the layers represent the connection between humans and the gods. Due to the influence of these two belief systems, Japan had a long history of being polytheistic, with many people revering gods for all purposes and matters in their lives.
Each of these theories are feasible and can honestly be identified as so based on the Japanese culture. It would be wrong to just pick only one, for there are many ways of life styles in Japan’s past, and it’s not common for different groups to celebrate the same theme, but with a different reasoning behind it.
DECORATIONS
The items used to adorn a kagami mochi is not random. Over several centuries a formalized practice was devised in how to visually present it. Below is an explanation of the items used as decoration, based on the image provided. Note that there are slight variations in the arrangement of the decoration, as well as items used, so this design is not written in stone as the only way to go.

- Shide (垂) – A new year decoration consisting of 2 strands of square-shaped papers hung on either side of the kagami mochi. This is a type of gohei (御幣)² used in Shintō practices. Generally white can be used, or can be mixed with red color. This is symbolic as warding away evil spirits that can bring bad luck and misfortune.
- Sanpō (三方) – A small stool to sit the kagami mochi on. Based on Shintō and Buddhist practices, this is a necessity. In the past, those of prestigious status could afford to obtain this. Present day, sanpō is an easily obtainable item at many outlets that can be purchased.
- Daidai (橙) – Originally a fruit called daidai (橙, bitter orange) would be placed on top of the kagami mochi. Nowadays, a small mikan (蜜柑, mandarin orange) is used in its place, although the title “daidai” still remains. The meaning behind using this fruit is “seimei saisei” (生命再生), which is “restore one’s life”³. Another thought on this is how daidai do not fall off of the tree they grow on even after ripening. This signifies having a strong family line.
- Urajiro – A type of leaf that comes from the fern species, called shida (歯朶) in Japanese. Two of these are used. This is not the only type of leaves that can be used for decoration of the kagami mochi, but this is the most common.
- Shihōbeni – This is a square white sheet of paper with red trimming placed underneath the kagami mochi. The meaning behind this is protection from misfortune, sickness, and disaster from all four cardinal directions.
Since all these are part of Japan’s culture, acquiring these items is relatively simple. This is especially true when new years is around the corner, for many stores and retail outlets will have these in stock and put out advertisements.
TABOO OF SPLITTING WITH SHARP INSTRUMENTS
For those who’ve seen images or an actual Kagami Biraki event would notice that a mallet is used to split open the kagami mochi. This is the same for a taruzake (樽酒), which is a barrel full of blessed sake used in the same fashion as kagami mochi at certain gatherings and events, especially at shrines. Although I’ve spoken about this in another article, I’ll reiterate it here as well since it’s related.

Early in the practice of Kagami Biraki, there are recordings about it once being known by the title “Kagami Wari” (鏡割り), which can be interpreted as “splitting the mirror”. This is because a bladed instrument was used to open up the kagami mochi. As a practice devised by prestigious military families, this makes sense as a to-go action. However, over time this was frowned upon due to its rather violent connotation; for a practice that was auspicious, “cutting” something that is said to be inhabited by a deity felt like a direct attack. It also didn’t help that the practice of seppuku (切腹, suicidal cutting of one’s belly) was a form of ritual punishment that forfeited a person’s life.

A movement was made to change the interaction with the kagami mochi that appeared both humane and non-violent, which is where the mallet was introduced. For this, one taps the top layer in order to “open” it, which means to separate it into two. This is a more acceptable depiction to release to blessing one would receive from the kagami mochi. On another note, it is OK to simply use both hands to separate the kagami mochi.
ENDING
This covers the significance of the kagami mochi during the new year, and the symbolism behind its presentation. As mentioned earlier, Kagami Biraki is not widely practiced nowadays throughout Japan, except by those families or groups that have reason to keep this tradition going. One thing for sure is there is still many images and public coverage on kagami mochi, much like this article, so it won’t easily be forgotten.
1) Hailing from Japan’s legendary tales. Known under many different titles, too numerous to mention. However, all point to the same goddess who shut herself in a cave after being the target of mean tricks by her brother, which brought darkness to the world. The other gods set into motion a plan to get her to come out, including having a mirror be the 1st thing she sees, to convince her that she was the most beautiful goddess of all.
This episode can be read in old texts such as the Kojiki (古事記) and Nihon Shoki (日本書紀).
2) Gohei is a stick consisting of streams of paper that is carried at the front of a procession or during a ceremony.
3) Daidai’s importance is based off of the tale concerning the deity Tajima Mori no Mikoto (田道間守命), and how he traveled to China to retrieve this bitter orange from China in order to make a medicine that would save the 11th emperor’s life.