Question: Osechi-ryōri, are traditional food,started in the Heian Period (794-1185), sometimes used to celebrate which annual festival with its own customs?

full_context: Document 1: Japanese cuisine: Japanese cuisine encompasses the regional and traditional foods of Japan, which have developed through centuries of social and economic changes. The traditional cuisine of Japan (和食 , washoku ) is based on rice with miso soup and other dishes; there is an emphasis on seasonal ingredients. Side dishes often consist of fish, pickled vegetables, and vegetables cooked in broth. Seafood is common, often grilled, but also served raw as sashimi or in sushi. Seafood and vegetables are also deep-fried in a light batter, as tempura. Apart from rice, staples include noodles, such as soba and udon. Japan also has many simmered dishes such as fish products in broth called oden, or beef in sukiyaki and nikujaga. Dishes inspired by foreign food—in particular Chinese food like ramen, fried dumplings, and gyōza—as well as foods like spaghetti, curry, and hamburgers have become adopted with variants for Japanese tastes and ingredients. Historically, the Japanese shunned meat, but with the modernization of Japan in the 1880s, meat-based dishes such as tonkatsu became common. Japanese cuisine, particularly sushi, has become popular throughout the world. In 2011, Japan overtook France in number of Michelin-starred restaurants and has maintained the title since.
Document 2: Greenery Day: The present observation of Greenery Day (みどりの日 , Midori no Hi ) as a national holiday in Japan stems from the celebration of the Emperor Shōwa's birthday on April 29 every year during the Shōwa era. In 1989, following the ascension of the current Emperor Akihito to the Chrysanthemum Throne, the name of the holiday was changed from "Birthday of the Emperor" to "Greenery Day". Officially, as its name suggests, it is a day to commune with nature and to be thankful for blessings. The day was renamed to "Greenery Day" to acknowledge the controversial wartime emperor's love for plants without directly mentioning his name. However, in practice it is seen as just another day that expands the Japanese Golden Week vacation.
Document 3: Chinese calendar: The traditional Chinese calendar is a lunisolar calendar which reckons years, months and days according to astronomical phenomena. s of 2017 , the Chinese calendar is defined by GB/T 33661-2017 "Calculation and promulgation of the Chinese calendar," which the Standardization Administration of the People's Republic of China issued on May 12, 2017.
Document 4: Tanabata: Tanabata (七夕 , meaning "Evening of the seventh") , also known as the Star Festival, is a Japanese festival originating from the Chinese Qixi Festival. It celebrates the meeting of the deities Orihime and Hikoboshi (represented by the stars Vega and Altair respectively). According to legend, the Milky Way separates these lovers, and they are allowed to meet only once a year on the seventh day of the seventh lunar month of the lunisolar calendar. The date of Tanabata varies by region of the country, but the first festivities begin on 7 July of the Gregorian calendar. The celebration is held at various days between July and August.
Document 5: Namasu: Namasu (膾 ) is a Japanese dish consisting of thinly sliced uncooked ("nama") vegetables and seafood, marinated in rice vinegar ("su") for several hours, pickling them slightly. "Namasu" was brought to Japan from China during the Nara period (710-794).
Document 6: Sushi: Sushi (すし, 寿司, 鮨 ) is the Japanese preparation and serving of specially prepared combined with varied such as chiefly seafood (often uncooked), vegetables, and occasionally tropical fruits. Styles of sushi and its presentation vary widely, but the key ingredient is sushi rice, also referred to as , or .
Document 7: Japanese New Year: The Japanese New Year (正月 , Shōgatsu ) is an annual festival with its own customs. Since 1873, the official Japanese New Year has been celebrated according to the Gregorian calendar, on January 1 of each year, New Year's Day (元日 , Ganjitsu ) . However, the celebration of the traditional Japanese New Year is still marked on the same day as the contemporary Chinese, Korean, and Vietnamese New Years.
Document 8: Sajibu nongma panba: Sajibu Nongma Pānba, also called Meetei Cheiraoba or Sajibu Cheiraoba, is the lunar new year festival of the people who follow the sanamahism religion of the Indian state of Manipur. The name Sajibu Nongma Pānba derives from the Manipuri words: Sajibu - the first month of the year which usually falls during the month of April according to Meitei lunar calendar, Nongma - first date of a Month, Pānba - to be. Literally, it means the first day of the month of Sajibu. Similarly, according to the Hindu lunar calendar, the lunar new year is celebrated on the same day as in Karnataka, Andhra Pradesh, Maharashtra and many other Indian states.
Document 9: Japanese calendar: Japanese calendar types have included a range of official and unofficial systems. At present, Japan uses the Gregorian calendar together with year designations stating the year of the reign of the current Emperor.
Document 10: Shimotsukare: Shimotsukare(しもつかれ) is a local Japanese dish served in Northern Kantō region of Japan, Tochigi Prefecture, Gunma Prefecture and Ibaraki Prefecture. The dish is generally served on hatsu-u-no hi (初午の日, literally; first day of horse in the month of February) together with sekihan as an offering to appease the legendary deity, inari. Shimotsukare is usually made by simmering vegetables, soybeans, abura-age (あぶらあげ or deep fried tofu skins) and sake kasu (酒粕, literally rice pulp from fermented sake). Common additional ingredients include grated raw radish (oroshi daikon) and carrots. The dish is also known as "shimitsukari", "shimitsukare" or "sumitsukare" in some areas.
Document 11: Kamameshi: Kamameshi () literally translates to "kettle rice" and is a traditional Japanese rice dish cooked in an iron pot called a "kama". Kamameshi originally referred to rice that was eaten communally from the kama. Kamameshi was originated in a town called Takeshitakama also known as Okunamikama. Coworkers or family members either ate directly from the kama pot or by transferring the rice to individual bowls. The term emerged in the late Meiji period, and is associated with the communal eating of rice in the aftermath of the 1923 Great Kantō earthquake. Later, similar to "takikomi gohan", kamameshi came to refer to a type of Japanese pilaf cooked with various types of meat, seafood, and vegetables, and flavored with soy sauce, sake, or mirin. By cooking the rice and various ingredients in an iron pot, the rice gets slightly burned at the bottom which adds a desirable flavor to the rice. "Kama" designed specifically to prepare kamameshi appeared on the market as the dish became popular across Japan, and the prepared kamameshi is placed directly on the table in its pot for the meal. A small-scale replica of the "kame" is used to create an individual serving of kamameshi, and the dish is now a popular "ekiben".
Document 12: Tsagaan Sar: The Mongolian Lunar New Year, commonly known as Tsagaan Sar (Mongolian: Цагаан сар , "Cagán sar" / ᠴᠠᠭᠠᠨ ᠰᠠᠷᠠ , ] or literally White Moon), is the first day of the year according to the Mongolian lunisolar calendar. The festival of the Lunar New Year is celebrated by the Mongols along with the people of the Arctic.
Document 13: Jidai Matsuri: The Jidai Matsuri (時代祭 , "Festival of the Ages") is a traditional Japanese festival (also called matsuri) held annually on October 22 in Kyoto, Japan. It is one of Kyoto's renowned three great festivals, with the other two being the "Aoi Matsuri", held annually on May 15, and the "Gion Matsuri", which is held annually from 17 to July 24. It is a festival enjoyed by people of all ages, participating in its historical reenactment parade dressed in authentic costumes representing various periods, and characters in Japanese feudal history.
Document 14: History of Japan: It is widely accepted that first human habitation in the Japanese archipelago can be traced back to prehistoric times. The Jōmon period, named after its "cord-marked" pottery, was followed by the Yayoi in the first millennium BC, when new technologies were introduced from continental Asia. During this period, in the first century AD, the first known written reference to Japan was recorded in the Chinese "Book of Han". Between the fourth century and the ninth century, Japan's many kingdoms and tribes gradually came to be unified under a centralized government, nominally controlled by the Emperor. The imperial dynasty established at this time continues to reign over Japan to this day. In 794, a new imperial capital was established at Heian-kyō (modern Kyoto), marking the beginning of the Heian period, which lasted until 1185. The Heian period is considered a golden age of classical Japanese culture. Japanese religious life from this time and onwards was a mix of Buddhism, and native religious practices known as Shinto.
Document 15: Osechi: Osechi-ryōri (御節料理 or お節料理) are traditional Japanese New Year foods. The tradition started in the Heian Period (794-1185). "Osechi" are easily recognizable by their special boxes called "jūbako" (重箱), which resemble "bentō" boxes. Like "bentō" boxes, "jūbako" are often kept stacked before and after use.
ground_truth: Japanese New Year