Ring in the new year with some traditional kagami mochi.

You’ve seen them in Japanese supermarkets, konbini and food stalls: white, snowman-like piles with an orange for a head, bringing good luck to all—these are kagami mochi (鏡餅). Translated literally, you might call them “mirror rice cakes,” and they’ve been a part of Japanese tradition since medieval times. But what are they, exactly?

The name comes from kagami mochi’s resemblance to a special kind of copper mirror that was popular back in the day.

Now, the mochi’s often wrapped in a thin film of plastic to preserve the cakes, which gives off a shiny, mirror-like cheerfulness. Kagami mochi come in different sizes and prices, but a basic one is made up of two glutinous rice cakes stacked on top of each other, with the larger cake on the bottom. This double stack is topped with a daidai (橙), a bitter citrus with a stem and a dark green leaf. Depending on how much you spend and what region you live in, your kagami mochi might also be adorned with other fruits and vegetables, a fan or decorative paper.

Displaying kagami mochi in your home is a classic way to welcome the new year. The mochi is thought to be infused with toshigami (年神): Shinto spirits that will bring all kinds of luck into the year to come, like a good harvest, blessings from ancestors and the power of life. People usually display at least one kagami mochi on a special stand at their Shinto altar or the tokonoma, an alcove in a house’s main gathering room. Each piece has symbolic meaning. The cake is a symbol of good fortune—doubling the cakes means double the goodness—and it also symbolizes years past and years to come. The name of the orange is a homonym for “generations” (代々), so it symbolizes the future generations of your family. Sometimes the whole thing is displayed on a sheet of kombu (dried kelp), a symbol of joy and pleasure.

All that good luck gets absorbed on January 11, Kagami biraki, or “opening kagami” day, when you “open” the mochi by breaking it into pieces, cooking it and eating up all those good vibes. Some people celebrate the breaking with a big party, while others keep their breaking low-key. Many people cook the pieces into zenzai, a sweet red bean soup, though styles vary from region to region.

The great mirror of etiquette

If there’s a supermarket near you selling kagami mochi, get out thereand grab some for your home! Just remember to follow these three rules.

DO NOT eat before the 11th

Kagami mochi are meant to be displayed until the big day, so keep your mitts off the mirror!

DO bring good fortune to every room

Starting at ¥200, kagami mochi are a fun and affordable way to spread luck throughout your home.

DO NOT cut with a knife

When “opening” day comes, use a hammer or your hands. Cutting with a knife has unlucky connotations.

Illustration by Chieko Watanabe