When is the Mushroom Ugly Burger available in Japan?

From Friday, May 8 through Sunday, May 17, 2026, at Burger King locations nationwide while supplies last.

How much does the Mushroom Ugly Burger cost?

1,090 yen for the single burger and 1,390 yen for the set, which includes small fries and a medium drink.

What's special about the 4-Cheese Craft Buns?

They're made by hand with Gouda, Egmont, Mozzarella, and Cheddar cheese, so only about one-third the usual bun volume can be produced.

What mushrooms are in the Mushroom Ugly Burger?

Two types of roasted mushrooms, eringi, and bunashimeji, paired with a Special Sour Cream Onion Sauce and flame-grilled beef.

How do I enter the 4-Cheese Craft Bun Keychain giveaway?

Use the Mushroom Ugly Burger Set entry coupon in the Burger King Official App between May 8 and May 17, 2026. 100 winners total.

Burger King Japan Mushroom Ugly Burger® Launches May 8, 2026

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Key Takeaways：Burger King Japan brings back its hit Mushroom series with a premium twist: the Mushroom Ugly Burger featuring four kinds of mushrooms and labor-intensive 4-Cheese Craft Buns. Available nationwide from May 8 to 17, 2026, with a single priced at 1,090 yen and a 100-winner keychain giveaway via the official app.

Burger King® Hit Mushroom Series Returns with New Premium Edition

BK Japan Co., Ltd. will launch the Mushroom Ugly Burger® as a limited-time offering at Burger King® locations nationwide from Friday, May 8 through Sunday, May 17, 2026. This newest entry in the wildly popular Mushroom series combines four varieties of mushrooms with the signature 4-Cheese Craft Buns used in the beloved Ugly Burger lineup, creating a hearty and authentic burger experience.

The Painstakingly Crafted 4-Cheese Craft Buns

The 4-Cheese Craft Buns used in the Mushroom Ugly Burger® are the result of extensive development and refinement. The pre-fermentation dough is evenly coated with tangy Gouda cheese, mild Egmont cheese, and subtly sweet Mozzarella cheese, then fermented and finished with hand-applied Cheddar cheese before baking.

Due to the extensive manual labor involved, only about one-third of the volume of regular buns can be produced, making them a truly premium item.

Four Mushrooms Meet a Special Signature Sauce

The burger features Burger King’s signature flame-grilled 100% beef patty topped with two types of roasted mushrooms, eringi mushrooms, and bunashimeji mushrooms, plus fresh lettuce, tomato, and onion. Everything is finished with a rich and creamy Special Sour Cream Onion Sauce made with sour cream, onion paste, and three herbs—oregano, thyme, and celery seed—along with mayo sauce.

Product Details

Product Name: Mushroom Ugly Burger®
Sales Period: Friday, May 8 – Sunday, May 17, 2026
Price: Single 1,090 yen, Set 1,390 yen

Classic Ugly Burger Lineup Also Available

Cheese Ugly Burger®: Single 940 yen, Set 1,240 yen
Double Cheese Ugly Burger®: Single 1,340 yen, Set 1,640 yen
Triple Cheese Ugly Burger®: Single 1,740 yen, Set 2,040 yen

4-Cheese Craft Bun Keychain Giveaway Campaign

To celebrate the launch, 100 lucky winners will receive an approximately 10cm oversized 4-Cheese Craft Bun Keychain through a lottery during the campaign period.

Campaign Period: May 8 (Fri) 8:00 – May 17 (Sun) 23:59, 2026
How to Enter: Use the dedicated entry coupon for the Mushroom Ugly Burger Set in the Burger King® Official App
Coupon Benefit: Get the regular 1,390 yen set for 1,290 yen (100 yen off)