Imoni is one of Yamagata Prefecture’s best-known traditional dishes. This hearty hot pot is centered around taro potatoes and commonly includes konnyaku, green onions, mushrooms, and seasonal vegetables.
When autumn arrives, people throughout Yamagata gather along riversides, beaches, and other outdoor locations for Imoni-kai, or Imoni gatherings. Families, friends, coworkers, and local communities come together around a large pot to cook and enjoy the dish while spending time together.
Taro comes into season around the time the rice harvest is completed, making Imoni closely associated with celebrating the autumn harvest. It is therefore much more than an ordinary hot pot. Imoni has become an important food tradition that brings people together and has been passed down through generations.
The tradition of Imoni-kai is said to date back approximately 300 years. In Yamagata, the first Sunday of September is traditionally regarded as the beginning of the Imoni season. From September through around December, large gatherings are held throughout the prefecture as people celebrate the flavors of autumn.
One of the most interesting aspects of Yamagata’s Imoni culture is the regional variation. The ingredients and seasoning differ from area to area, meaning that two dishes called “Imoni” can have distinctly different flavors.
In the Shonai region, Imoni is typically made with pork and miso. The savory flavor of pork combines with the richness of miso and pairs particularly well with the soft, hearty texture of taro.
In the inland areas of Yamagata, beef and soy sauce are the traditional combination. The savory flavor of beef blends with the soy sauce-based broth to create a relatively light and clean-tasting Imoni.
In the Okitama region, a style using chicken has been passed down through generations. Chicken is simmered together with taro and other ingredients to create a distinctive regional version of the dish.
In the Murayama region, versions using both beef and pork can also be found. Soy sauce is commonly used as the foundation of the seasoning, while individual communities and families add their own variations.
There are several theories about when and how Imoni originated, and its exact beginnings remain uncertain.
One of the best-known theories dates back to the Edo period (1603–1868). It is said that boatmen traveling along the Mogami River cooked cod and taro together in a pot. During the era when river transportation flourished along the Mogami River, boatmen may have cooked readily available ingredients outdoors along the riverbanks, creating a tradition that eventually developed into Imoni.
Another theory suggests that workers involved in construction along the Mamigasaki River in Yamagata City began cooking taro together as a simple meal.
Neither theory has been conclusively established as the true origin. Nevertheless, both stories reflect an important element of Imoni culture: people gathering outdoors, cooking in a large pot, and sharing a meal together.
One of the most famous celebrations of Yamagata’s Imoni culture is the Japan’s Largest Imoni Festival, held every September. It has become one of the defining signs of autumn in Yamagata and attracts visitors from both inside and outside the prefecture.
The festival serves the soy sauce-based Imoni associated with the Murayama region. An astonishing 30,000 servings are prepared using a gigantic cooking pot, creating an impressive spectacle that showcases the scale of Yamagata’s Imoni tradition.
The centerpiece of the festival is the enormous cooking pot known as Nabetaro, which measures approximately 6 meters in diameter. It is used to prepare a huge quantity of Imoni using locally produced ingredients from Yamagata.
Taro: Approximately 3 tons
Beef: Approximately 1.2 tons
Konnyaku: Approximately 3,500 pieces
Green onions: Approximately 3,500 stalks
Soy sauce: Approximately 700 liters
Japanese sake: Approximately 50 sho
Sugar: Approximately 200 kilograms
Yamagata water: Approximately 6 tons
These enormous quantities of ingredients are cooked using approximately 6 tons of firewood. The fire is lit at around 6:00 a.m., and the ingredients are slowly simmered for approximately three hours so that the flavors can thoroughly penetrate the taro and other ingredients.
Once the giant pot of Imoni is ready, the scale of the operation is very different from an ordinary home-style hot pot. A large backhoe excavator is used to scoop the finished Imoni from the enormous pot and serve it to festival visitors.
The sight of a giant pot alongside a full-size excavator is one of the most spectacular scenes at the festival and has become an iconic image of Yamagata’s Imoni culture.
The Japan’s Largest Imoni Festival is not simply about preparing an enormous quantity of food. Another important feature is its emphasis on locally produced Yamagata ingredients.
The taro used for the festival is planted in May by the organizers and local volunteers, who carefully cultivate the crop until harvest. The beef is Yamagata Beef, a Japanese Black cattle variety, while ingredients such as konnyaku and green onions are also sourced from Yamagata Prefecture.
By cooking these locally grown ingredients together in one enormous pot, the festival brings out the flavors that are closely associated with Yamagata’s food culture.
Imoni-kai is about much more than enjoying a delicious meal. Gathering along a riverbank or another outdoor location and sharing a large pot of Imoni provides an opportunity for families, friends, coworkers, and local communities to talk, laugh, and spend time together.
Traditionally said to have continued for around 300 years, Imoni-kai remains an important part of Yamagata’s cultural life. It is a way of celebrating the harvest while strengthening connections between people.
Imoni may be a simple hot pot centered around taro, but its regional variations reveal the diversity of Yamagata’s culinary culture. Differences in meat, seasoning, and ingredients allow visitors to experience distinct local flavors across the prefecture.
If you visit Yamagata in autumn, be sure to try Imoni and, if possible, experience an Imoni-kai where people gather around a large pot and share the meal together. It is a warm and memorable way to experience the food, traditions, and welcoming community spirit of Yamagata in autumn.