Heat the soy milk to about 75℃. Remove from heat, then add the nigari. Gently stir twice, then let sit until it starts to stiffen.
For oboro-dofu (half-curdled tofu), let sit until it sets, then it's done.
After about 10 minutes, when it begins to set, pour it into a cheese cloth and drain the excess liquid. It's ready when it reaches your desired firmness.
Story Behind this Recipe
Make homemade tofu from homemade soy milk.
If the heat under the tofu is too high or too low, it will not set properly. Store-bought soy milk is too thin, so it is not suitable for making homemade tofu. Try it with your own thick homemade soy milk.