It was said to be the court-lady language that came from the color of soy-sauce, or it was said to have a connection with the fact that soy-sauce in large quantities was produced along the foot of Mt. Tsukuba in the Edo period.
醤油の色から来た女房詞、または江戸時代に筑波山麓で醤油が多産されたことからとも言われる。