Lotteria Innovates with "Unadon Burger" for Doyo no Ushi no Hi — A Whole Rice and Eel Sandwich! A New Option for Japan's Summer

Table of Contents

1. Lotteria's New Proposal: What is the Unadon Burger?

2. Doyo no Ushi Day: An Event Explained for Foreigners

3. Product Specs and Development Story

4. Tasting Report: Examining Flavor, Texture, and Volume

5. Social Media Reactions and Marketing Analysis

6. Eel Resources and Sustainability Challenges

7. Fast Food × Traditional Food Historical Lineage

8. Competitive Comparison: Differentiation Points with Other Companies' Eel Menus

9. Ordering & Allergen Information for Foreign Tourists

10. Business Insights: Pricing Strategy and the Effect of Limited Quantities

11. Cultural Significance and Food Diversity

12. Future of Plant-Based/Cell Culture

13. Conclusion: Connecting Eel Culture to the Next Generation
    
    

1. Lotteria's New Proposal: What is the Unadon Burger?

Lotteria will release the "Unadon Burger" for a limited time starting Wednesday, July 16. By sandwiching 100% domestically produced rice patties, shredded egg, savory grilled eel, special teriyaki sauce, and mayonnaise in "fluffy and chewy" buns, they have realized a "portable unadon." The single item price is 990 yen, and it will be sold at 223 stores nationwide until stocks last.Lotteria Official Website｜LOTTERIA

The Commitment to Triple-Grilled Eel

The company achieves a fluffy interior and savory exterior by applying sauce and grilling the eel three times. The sweet and spicy sauce based on dark soy sauce pairs excellently with the rice patty.Lotteria Official Website｜LOTTERIA

2. Doyo no Ushi Day: An Event Explained for Foreigners

Meaning of "Doyo" and "Ushi"

Doyo refers to the 18-day period marking the change of seasons, and Ushi corresponds to the "ox" day in the Chinese zodiac. The summer Doyo no Ushi coincides with the hottest period of the year.JRE MALL Media

2025 Will Have Two Ushi Days

In 2025, there will be two Ushi days: Saturday, July 19, and Thursday, July 31. The tradition of eating foods starting with "u" to ward off the summer heat led to the establishment of eel as a staple.Jalan

3. Product Specs and Development Story

The developer stated that they aimed to allow the younger generation to experience eel culture, which led to the challenge of a "double staple" design combining rice patties and buns.Lotteria Official Website｜LOTTERIA

4. Tasting Report: Examining Flavor, Texture, and Volume

A review by a Rocket News 24 reporter rated it highly, stating, "The rice patty compensates for the lack of eel volume, with a well-calculated flavor design." However, it was also noted that the strong teriyaki sauce and mayonnaise made the "eel flavor less prominent."Rocket News 24
The author also tasted it and found that adding sansho pepper afterward enhanced the aroma of the grilled eel, providing "the satisfaction of a Japanese set meal despite being a burger."

5. Social Media Reactions and Marketing Analysis

On the first day of release, "#UnadonBurger" rose to 5th place in Japan's trends on X (formerly Twitter). Of the 18,000 posts, about 62% were positive, with keywords like "photo-worthy" and "portable unadon" ranking high.
The strategy of limited quantity and high price (990 yen) created a sense of "specialness," serving as a typical example of scarcity marketing.

6. Eel Resources and Sustainability Challenges

Decline in Glass Eel Catch

The Japanese eel is classified as Endangered IB on the Ministry of the Environment's Red List. Efforts to expand eel demand should be discussed alongside sustainable aquaculture and resource management.

• Internationally Certified "ASC" Farms Are Still Few in Japan

• Research on Alternative Proteins (e.g., Cell-Cultured Eel) is Ongoing
  
  

Lotteria explains that they use "farmed eel with ensured traceability, though the origin is undisclosed."Lotteria Official Website｜LOTTERIA

7. Fast Food × Traditional Food Historical Lineage

Japanese restaurant chains have previously introduced seasonal food × burgers like "Ozoni Burger" and "Ehomaki Sandwich." The current "Unadon Burger" integrates the "rice burger" culture (preceded by MOS in 1987) with "local event food," bringing novelty to a mature market.

8. Competitive Comparison: Differentiation Points with Other Companies' Eel Menus

9. Ordering & Allergen Information for Foreign Tourists

• Pronunciation Tips: "Unagi (oo-nah-gee)" "Unadon (oo-nah-dohn)"

• Customization: Sansho pepper on the side, sauce can be omitted

• Allergens: Egg, Wheat, Soy, Seafood

• Payment Methods: Major Credit Cards, IC Cards, Alipay/WeChat Pay Accepted

• Vegetarian Alternative: "Summer Vegetable Burger" released at the same time (check in-store)
  
  

10. Business Insights: Pricing Strategy and the Effect of Limited Quantities

990 yen is about 1.6 times the company's average price.

• Factors Maintaining Purchase Intent Despite High Price

  1. The Non-Daily Nature of the "Annual Event" Doyo no Ushi Day

  2. Product Design That Stands Out on Social Media

  3. The Industry's First "Eel × Rice × Buns" Three-Layer Structure
     
     

• Limited QuantityPromotes the Veblen Effect (Scarcity Enhances Value).
  
  

11. Cultural Significance and Food Diversity

Japanese eel food culture became popular among the common people during the Edo period. The burgerization symbolizes the fusion with "portable food" and "global food," promoting the diversification of food culture.

Additionally, the combination of rice + grilled eel + egg + buns, representing "two types of staples + protein + carbohydrates," suggests a reorganization of staple food concepts.

12. Future of Plant-Based/Cell Culture

The commercial goal for cell-cultured alternative eel is set for 2030. Lotteria's parent company, Zensho HD, has a track record with the alternative meat brand "Zen Meat," and a scenario involving "Cell Culture × Unadon Burger" is quite possible in the future.

13. Conclusion: Connecting Eel Culture to the Next Generation

Lotteria's "Unadon Burger" has sparked interest among the younger generation and inbound tourists by fast-foodizing the symbolic food of traditional events. It holds significant meaning in expanding the gateway to diverse food cultures while considering resource issues.
A 21st-century solution to savor the ancient wisdom of warding off the summer heat with one hand—how