A soybean can turn up at different stages and in very different forms. That does not make those forms interchangeable in a recipe.
The dry pantry ingredient
A bag of dry soybeans belongs to the ingredient side of the story. Follow the cooking or fermentation instructions written for that ingredient. Do not assume a dry-bean photograph is a ready-to-eat dish.
The green snack
Edamame refers to green soybeans used in a different culinary form. It makes a useful illustration of the same crop’s range, not a shortcut for replacing the beans in a tested natto process.
The finished fermentation
Ready-to-eat natto is already a prepared food. Our quick recipes start there. Home fermentation is a separate project, using an appropriate starter and its specific directions.
Label the photograph honestly
Our ingredient features show what their captions say they show. A green soybean photo is not advertised as a close-up of finished natto.