Japanese horseradish (wasabi) is produced in regions with pristine cold streams. The main production areas are Amagi on the Izu Peninsula, Hotaka in Nagano Prefecture and Okutama in greater Tokyo. High-quality wasabi, recognized by its light green stem, has a strong flavor and refreshing aroma. The area closest to the stems contains bitter flavors and should be discarded before grating. It is also said that wasabi grated on shark skin oxidizes more slowly and retains its natural flavor better than when prepared using a metal grater. Wasabi has anti-bacterial properties, acts as a deodorizer, improves blood flow, aids in digestion, and is essential at restaurants where raw fish is served.