Step 1

Wash the soybeans and soak for 9 hours in the summer to 12 hours in the winter (I used Instant Pot insert bowl for soaking to wash less dishes).

Step 2

Drain soybeans in a medium colander.

Step 3

Place the beans back into the pressure cooker bowl, and add filtered water to cover the beans by an inch.

Step 4

Use the 'bean' setting on Instant Pot, or cook on high pressure for 30 minutes. Let the pressure release naturally when done.

Step 5

Discard any extra liquid, if any, using a sieve, and place the soybeans back into the bowl of the pressure cooker.

Step 6

Dissolve 1 special spoonful of Nattomoto powder in 1 tablespoon of sterilized water.

Step 7

Pour the Nattomoto solution over the beans, and stir them carefully with a spoon.

Step 8

Divide the soybean mixture between the containers, cover with sterilized cheese cloth, and cover the containers with lids (I didn't snap my lids, so the beans were not air-tight).

Step 9

Place the containers into a preheated oven maintaining the temperature around 100º-104ºF (38º-40ºC). Let the natto ferment for 22-24 hours.

Step 10

Remove the natto from oven, and transfer to refrigerator for a night. The next morning, the natto is ready.