Tane-mizu (Seed water)
Japanese: 種水（たねみず）
Liquid from a previous batch carrying microorganisms to help start fermentation.
Tane-mizu is cooking liquid or tamari from a previous batch, containing active microorganisms.
Adding it accelerates fermentation startup and carries forward similar flavors. Also adjusts moisture. Like a baton connecting each batch to the next. For first batches, mixing in a small amount of finished miso works. Its resident microorganisms help start the new batch. Ancestral wisdom propels each step. Fermentation is a cyclical practice.