Natto Day is observed worldwide on July 10 and is dedicated to celebrating natto, a traditional Japanese food made from fermented soybeans. The holiday is particularly popular among Japanese cuisine lovers and highlights natto's unique characteristics, including its powerful odor and slimy texture, which some compare to pungent cheeses. The fermentation process involves mixing cooked soybeans with the hay bacillus (Bacillus subtilis var. natto) and allowing them to ferment at 40 °C (104 °F) for up to 24 hours. Natto is often served as a breakfast dish alongside rice, Japanese bunching onion, karashi mustard, daikon, and soy sauce, and can also be incorporated into various foods like miso soup, sushi, and even ice cream. The date of July 10 was chosen because the numbers 7 and 10 sound similar to "natto" in Japanese. However, it is important to note that natto's distinct smell and flavor make it an acquired taste, not universally appreciated by all Japanese people.