It is said that there are regional differences in terms of such characteristics as saltiness and sweetness. Soy sauce is closely related to the food culture of each region, and the characteristics of soy sauces are likely influenced by the local food culture.
For example, Kyushu soy sauce is often said to be sweet. However, people in Shikoku or people who live near the Japan Sea in Chugoku or in the Chubu region also prefer sweeter soy sauce. This might be because the sweeter soy sauce goes well with fresh fish such as sashimi.
Usukuchi soy sauce is mainly used in the western part of Japan and is also produced mainly in Hyogo prefecture. Therefore, it is not common for people in the Kanto region to use Usukuchi soy sauce.
In Aichi prefecture, people prefer Tamari soy sauce rather than regular (Koikuchi) soy sauce. White soy sauce is also produced mainly in Aichi prefecture.