Newcomers to Japan are often a little taken aback by the many decidedly non-Japanese condiments, such as ketchup and Worcestershire sauce, that are used in everyday cooking. And in particular mayonnaise: Usually reserved for sandwiches, salad dressing and dipping sauces for chilled seafood in the West, is used with abandon in Japan. The popular recipe site Cookpad lists more than 134,000 recipes containing mayonnaise, including hot dishes and desserts. There are even recipes for cakes containing mayonnaise in the batter or the icing.

Originating in Spain and France in the 18th century, mayonnaise was introduced to Japan in 1925 by Toichiro Nakashima, who had first encountered it as a young student in the United States. Six years after opening his own food production company in 1919, he used another American icon — a baby doll with googly eyes invented by Rose O'Neill — as the trademark for his new bottled sauce; and so Kewpie Mayonnaise was born.

According to the official history of the Kewpie Corporation, Nakahata wanted to introduce this rich sauce to his homeland to encourage young people to take in more nourishment, so that they could grow as strong and tall as their Western counterparts. To this end he formulated his mayonnaise using only fat-rich egg yolks rather than the whole egg, and doubled their amount. He also sweetened the sauce a little using apple vinegar, and later on a little monosodium glutamate (MSG) was also added to the formula, making it a distinctly Japanese-tasting concoction.