My favorite non-alcoholic drink in Japan is called Calpis Water. This beverage is an non-carbonated drink, manufactured by Calpis Co., Ltd., headquartered in Shibuya, Tokyo, with a light, somewhat milky, and slightly acidic flavor, similar to plain or vanilla-flavored yogurt (I like yogurt). Its ingredients include water, nonfat dry milk and lactic acid, and is produced by lactic acid fermentation.
Its carbonated variety, known as Calpis Soda, is also widely available in Japan – I have tried this also, but I don’t like it as much as Calpis Water. According to the Calpis website, there are other Calips flavors such as Mango, Strawberry and Lychee.