Natto are fermented soy beans. They are essentially half decomposed by bacteria! They are coated with a slippery, cheesy, stringy sauce. They don't smell very good at first whiff. But they are an acquired taste, so if you keep trying them, you, too, will eventually grow to love natto. I know a person who loves them so much, he maintains a natto stash in his freezer! This natto is from Ichibei, and it comes with tuna, which is a very nice combination.