The iconic two-hole design on the classic Kikkoman glass dispenser cap was engineered with brilliant functional precision by industrial designer Kenji Ekuan. The dual spouts serve a dual mechanical purpose: when you tip the bottle to pour, one hole acts as an air vent to ensure a smooth, uninterrupted stream of liquid. More importantly, it functions as a "control hole"—by simply placing a finger or thumb over one opening, you instantly restrict the airflow, allowing you to regulate the pour down to a precise trickle or stop it entirely without dripping down the sides of the bottle.