Since early this year, Yamakawa Jozo, a soy sauce brewery based in Gifu prefecture, has been selling a type of Tamari soy sauce specially designed for use on ice cream. With the sauce's rising popularity and a growing number of restaurants using it on their dessert menus, the company sold 5,000 bottles (70 ml for 350 yen/$3) in the second half of August.
A small amount of the rich, dark brew is said to give vanilla ice cream a caramel-like flavor, while a more liberal dose apparently makes vanilla ice cream taste more like mitarashi-dango (skewered rice dumplings covered in sweet sauce).
According to the president of Yamakawa Jozo, the company developed the soy sauce specifically for use with vanilla ice cream, but consumers have come forward with a number of unexpected recipes. In addition to claims that it goes well with other ice cream flavors like strawberry and chocolate, fans of the special sauce say it tastes great on kaki-gori (shaved ice) and on toast, and that it makes a great mixer for shochu (distilled liquor).