Fermentation in miso products is called waki in Japanese. In this study, we tried to understand waki as a phenomenon generated not in the miso product itself but in the liquid phase existing in the miso product. Liquid culture conditions suitable for investigation of the waki phenomenon became evident. It was proved that liquid medium could be used as a model for waki tests of miso products. In the relationship between ethanol concentration and sodium chloride concentration, border conditions governing whether the waki phenomenon would occur or not were discovered.