About half a day before you intend to eat it, transfer the frozen natto from the freezer to the refrigerator to allow it to defrost gradually. Keep it in the refrigerator until just before you intend to eat it.
The quality of the natto will be adversely affected by a rise in temperature. If you leave it for an extended period at room temperature, the natto bacillus that had been dormant in the cold air will reawaken and begin fermentation again. This may change the viscosity and fragrance of the natto in undesirable ways.
In its storage container, the sticky soybeans tend to stick to one another and form clumps. The beans will also tenaciously stick to the container itself. It is possible to mix the natto within the storage container, but until you become accustomed to doing this, we recommend that you transfer the natto to a bowl or other vessel so you will be able to mix it thoroughly.
Agitating and mixing the natto well increases its viscosity. This also produces strong fine threads and makes the natto look more "natto-like." The standard number of strokes for mixing and stirring natto is generally 30 to 50 strokes. However, some people only use about a dozen strokes, just enough to separate the soybeans, while others use several hundred strokes or more. The more it is mixed and stirred, the more the natto will take its proper form, like a flower bud blooming.
When the natto has been mixed and stirred and it has developed threads, you may add sauce or shoyu to adjust its flavor. Common ways of eating natto include adding vinegar, olive oil, Japanese mustard or egg.
... and begin eating!