You can mix in tuna instead of the green onions to make it a tuna, miso, and mayonnaise flavor (as shown in the background of the photo).
Story Behind this Recipe
My husband's brother taught me this recipe. He insists that this is way to eat natto. He recommends it to me whenever we talk about cooking. When I decided to give it a try, it tasted much better than I'd imagined.
Add the accompanying sauce from the natto pack to taste. If you like your natto to be strongly flavored, try adding a few drops of soy sauce. If you like yours slightly spicy, mix in some ra-yu, doubanjiang, or yuzu pepper. My brother-in-law recommends both the green onion miso mayonnaise and the tuna miso mayo.