Plum Day (Ume no Hi)

What Is Plum Day?

June 6 is "Plum Day" (Ume no Hi) every year. The date traces back to the 17th day of the 4th month of Tenbun 14 (1545, during the Muromachi period), which corresponds to June 6 on the modern calendar. According to legend, when Emperor Go-Nara performed a ritual at the Kamo Shrine festival in Kyoto (the Aoi Festival), plums were offered and prayers made, whereupon thunder rolled, heavy rain fell, and a bountiful harvest followed. The day was established in 2006 by the "Kishu Ume no Kai" (Kishu Tanabe Ume Promotion Council) of Tanabe City, Wakayama Prefecture, a major plum-growing area, and is registered with the Japan Anniversary Association.

The Legend Behind Plum Day and the Origin of "Tsuyu" (Rainy Season)

According to the story, a drought had left farmers unable to plant rice. In 1545, Emperor Go-Nara offered plums at Kamo Shrine and prayed, and soon thunder rumbled and heavy rain fell, soaking the fields. People are said to have called this blessed rain "baiu" (plum rain), thanked the plums, and begun giving plums as gifts to ward off misfortune and invite good luck. The more commonly cited origins of the word "baiu" (梅雨), however, trace it to China -- as the rain that falls when plums ripen, or as a play on "baiu" (黴雨), "mold rain."

The History of Plums in Japanese Culture

The Japanese plum (ume) is believed to have originated in China and was introduced to Japan before the Nara period. In the Nara period, the word "flower" often referred specifically to plum blossoms, and the Man'yōshū poetry anthology contains around 120 poems about plums. The current era name "Reiwa" was taken from the preface to the Man'yōshū's "Thirty-Two Poems on Plum Blossoms." Even after cherry blossoms took over as the centerpiece of flower-viewing in the Heian period, plums remained deeply woven into daily life through umeboshi (pickled plums) and plum wine.

• Man'yōshū: Many poems celebrate plum blossoms, such as Ōtomo no Tabito's verse likening falling plum petals in his garden to snow drifting down from the sky.
• Sugawara no Michizane: Famous for his poem asking the east wind to carry the fragrance of plum blossoms to him — the god of learning, Michizane, deeply loved plums, and plum trees remain inseparable from Tenjin shrine worship to this day.
• Umeboshi (pickled plums): Valued since long ago as a food that keeps well, umeboshi are said to have been carried as field rations in the Sengoku period.

Plum Components and Food Culture

• The source of the sourness: Ume's strong tartness comes from organic acids such as citric acid and malic acid.
• Umeboshi and bento: The acidity and salt of umeboshi help food keep, making them a classic in rice balls and bento boxes.
• Bainiku ekisu (plum extract): A traditional product made by boiling down green plum juice for a long time. Research has been conducted on mumefural, a compound formed during heating.
• Don't eat green plums raw: The pits and other parts of unripe plums contain substances that can form harmful compounds when broken down, so they are enjoyed after processing into plum wine or umeboshi.

Plum-Growing Regions and How to Enjoy Plum Wine and Umeboshi

Wakayama Prefecture is Japan's largest plum-producing region, accounting for more than 60% of the domestic harvest. In particular, the "Nanko-ume" variety, prized for its thick flesh and small pit, is prized as a premium variety for umeboshi and plum wine. June is harvest season for green plums, and supermarket shelves fill up with them around this time.

• Try making your own plum wine, plum syrup, or plum jam using green plums.
• Pickle ripe (yellow) plums into umeboshi, and try the "doyō-boshi" of sun-drying them in midsummer.
• Enjoy plum-based products like umeboshi, ume-kombu tea, and plum juice as a way to reflect on the history of this beloved fruit.