This is ‘natto’, a must food for the Japanese-style breakfast. As you can see, it doesn’t look great. It is sticky and smells bad, too. But many Japanese love it. Actually, this is always one of the foods Japanese miss the most in foreign countries where it isn’t available.
Natto is fermented soy beans. It is usually eaten with mustard, soy sauce and minced green onions. Some people like to mix with a raw egg (it may sound awful, too.) to make its taste milder. This goes well with hot rice!
Since natto is rich in vegetable protein, it is also an ideal food for vegetarians. If you find it in buffet at your hotel, please try. You will definitely amaze Japanese around and can be a hero!