Boil dehulled beans in 2 parts water for 6 hours till soft. Add water every hour to keep beans immersed. After adding water, stir, skim foam and floating hulls off the top. The beans are done when they turn to puree pressed between thumb and finger. Drain. Puree in 2 cup increments in foodprocessor with Tbs old natto and 1/4 cup water till smooth.

Ladle into glass baking dish, make a 2” layer. Cover with shrinkwrap. Put in oven with oven light on, top shelf is usally 110F-120F degrees, bottom shelf is 100F degrees, put mash at 100F to 120F degrees. Taste every six hours. When you like the taste, Cool in fridge to stop fermentation. Done! Freeze three tubs, use one, keep well sealed.