Kamebishi's 20-year-aged soy sauce is the most expensive soy sauce in the world, sometimes selling for $125 for less than 4 tablespoons. The soy sauce has been made using the same family recipe since 1753 and follows the traditional mushiro koji method, in which each step takes years to complete. For comparison, most popular soy sauces can cost less than a bottle of water, and other aged artisanal soy sauces generally cost around $40. In 2001, Kaori Okada, the 18th-generation owner of Kamebishi, left her career in the travel industry to save her family's struggling company using a combination of traditional methods and new innovations. Here's why Kamebishi's 20-year-aged soy sauce is so expensive.