Mutton Day (Yōniku no Hi)

What Is Mutton Day?

Every year on April 29th is "Mutton Day" (Yōniku no Hi). The date comes from a wordplay on numbers: "4" (yo), "2" (ni), and "9" (ku) combine to spell "yōniku," meaning lamb or mutton. The day was established in 2004 by the Jingisukan Food Promotion Council (Jingisukan Shoku Fukyū Kakudai Sokushin Kyōgikai) to deepen understanding of jingisukan — Japanese-style grilled lamb, part of Hokkaido's traditional food culture — and to promote lamb and mutton as a whole. It falls at the start of Golden Week, and in Hokkaido, grilling jingisukan under the cherry blossoms is a familiar spring scene.

The History of Jingisukan in Japan

Japan's taste for lamb and mutton is rooted in a national policy aimed at producing wool domestically.

• Starting with wool sheep: In the Taishō era, the government launched a plan to increase sheep numbers to secure wool for military uniforms and other uses, setting up sheep-breeding stations across the country. Efforts to find tasty ways to eat the meat of these wool sheep are said to have helped jingisukan spread.
• Becoming Hokkaido's soul food: After the war, jingisukan took root in Hokkaido as a dish for home meals and outdoor gatherings. There are two main styles — marinating the meat before grilling, or dipping it in sauce after grilling — and preferences differ by region. Jingisukan has been selected as a Hokkaido Heritage item.

The Secret of the Jingisukan Pan

The jingisukan pan is shaped like a dome or helmet. Meat is grilled on the raised center, while the juices and sauce run down to cook the vegetables around the edge. The grooves are also said to help drain excess fat.

Interesting Facts About Lamb and Mutton

• Lamb vs. mutton: Generally, meat from sheep under one year old is called "lamb," while meat from older sheep is called "mutton." Lamb is milder and more tender, while mutton has a stronger flavor.
• Eaten around the world: Lamb and mutton are enjoyed in the Middle East, Europe, Oceania, and beyond. Much of the lamb sold in Japan is imported from Australia and New Zealand.
• The "sheep" in kanji: A number of kanji with positive meanings — such as 美 (beauty), 義 (righteousness), and 善 (goodness) — contain the element for "sheep," suggesting the animal's long-standing importance.
• Fat that sets quickly: Sheep fat has a relatively high melting point and firms up as it cools, so lamb is best eaten hot off the grill.
• A source of carnitine: Lamb is known for containing relatively high amounts of L-carnitine, a compound involved in turning fat into energy.

Tips for Enjoying Mutton Day

• Enjoy jingisukan or lamb chops for lunch or dinner
• Host a jingisukan party around a hot plate with family or friends
• Try cooking with spices and herbs that pair well with lamb, such as cumin or rosemary
• Compare the "marinated first" and "sauce afterward" styles of jingisukan

Kick Off the Holidays Around a Jingisukan Grill

April 29th is a day to savor the story of lamb in Japan — from the era when sheep were raised for wool to jingisukan's place as a beloved Hokkaido dish. At the start of Golden Week, gather with family and friends around the grill and enjoy lamb anew.