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, Emperor Go-Nara offered plum branches at the Kamo Shrine festival in Kyoto (now known as the Aoi Festival), and a long-running drought finally broke as blessed rain began to fall. This rain is said to have given rise to the word "tsuyu" (plum rain), Japan's term for the rainy season. The anniversary was officially registered with the Japan Anniversary Association in 2006 by the Kishu Tanabe Ume Promotion Council (Kishu Ume Association).

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

During the Muromachi period, Japan faced years of poor weather, threatening crop failures and severe famine. In 1545, Emperor Go-Nara offered plum branches at Kamo Shrine and prayed for rain. Soon after, thunder rumbled and heavy rain fell, soaking the fields. People rejoiced, believing the plum had "called the rain," and according to one theory, this is how the seasonal rains came to be called "tsuyu" — literally "plum 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. It was so beloved that, until the early Heian period, the word "flower" often referred specifically to plum blossoms — the Manyoshu poetry anthology contains around 119 poems about plums. 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.

• Manyoshu: Many poems celebrate plum blossoms, including verses about waiting eagerly for white plum flowers to bloom again each spring.
• 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 ancient times for their antibacterial and fatigue-relieving properties, umeboshi were a prized preserved and portable food for samurai and farmers alike.

The Nutrition and Health Benefits of Plums

• Citric acid: Plums are rich in citric acid, which is believed to help break down fatigue-causing substances and relieve tiredness.
• Antibacterial properties: Compounds in umeboshi, such as catechic acid and picric acid, help suppress bacterial growth — one reason they're valued during summer, when food poisoning is more common.
• Plum extract (mumefural): A compound formed when plums are heated, currently being studied for its potential to improve blood flow and help prevent arteriosclerosis.
• Alkaline-forming food: Despite their sour taste, plums turn alkaline once digested and are believed to help keep the blood slightly alkaline.

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

Wakayama Prefecture is Japan's largest plum-producing region, accounting for about 60% of domestic production. In particular, the "Nanko-ume" variety, prized for its thick flesh and small pit, is considered top-grade for both 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 — letting them dry in the sun and age for two to three years deepens their flavor.
• Enjoy plum-based products like umeboshi, ume-kombu tea, and plum juice as a way to reflect on the history and health benefits of this beloved fruit.