Soy Sauce is very important in japanese cooking and Japanese soy sauce (shoyu) is very strong in taste compared to Chinese soy sauce. I've been searching for halal japanese soy sauce for years. Finally after asking halal japanese outlets in Singapore like Ramen Ten and Hei Sushi, i've found the halal Japanese soy sauce that i can use for my japanese cooking. I thought KIKKOMAN is halal but after talking to their Japanese manager and he claimed that none of their KIKKOMAN product is halal as they added alcohol at the last stage of process. So the halal Japanese soy sauce that Ramen Ten and Hei Sushi are using is YAMASA brand. Their soy sauce does not add any alcohol. I've read online of how they process their soy sauce and it looks 100% halal to me. But take note that not all of their products are halal. Check out their website if u are interested to know more:
http://www.yamasa.com