Japanese bath additives (called nyūyokuzai) are products added to bathwater—powders, salts, tablets, or liquids—to change the bath’s scent, color, and overall “feel.” In Japan, where the evening bath (ofuro) is treated as a daily reset rather than a quick wash, nyūyokuzai are a small but very common ritual: you choose today’s mood, pour it in, and let the bathroom become a tiny seasonal spa. This guide explains what nyūyokuzai are, how they differ from onsen, the main types, and how Japanese people actually use them at home. What Is Nyūyokuzai? Nyūyokuzai is a bath additive: a product designed to ...
