Matsumoto natto is a traditional Japanese food made from fermented soybeans, originating from the city of Matsumoto in Nagano Prefecture. It is known for its distinctive sticky texture and strong flavor, which can be an acquired taste for some. The fermentation process involves the use of a specific bacterium called Bacillus subtilis, which contributes to its unique characteristics. This dish is often served with rice and can be topped with ingredients like green onions or soy sauce. Matsumoto natto is rich in protein, vitamins, and probiotics, making it a nutritious addition to meals. It is particularly popular for breakfast in Japan.