Soy sauce (shoyu) is the representative condiment of Japan and a primary seasoning for the dipping of sushi and sashimi. It is also simmered together with sweet cooking sake (mirin), sake and fish stock (dashi) to produce nikiri, the thick sauce brushed on eel (unagi) and conger eel (anago). As shoyu contains a lot of amino acids, umami components and anti-bacterial properties, one cannot hold a conversation about the preservation of Japanese foods without mentioning shoyu. Eel and soba restaurants in the late Edo era led to the development of shoyu as we know it today. Although there are many ways to grade shoyu, it has been common since the Edo period to mark especially high grade shoyu as “上” (high).