Can you tell the difference of Udon soup between eastern and western Japan?

Do you know the difference of Udon-soup between Tokyo and Osaka?
If you eat Udon both in Tokyo and in Osaka, you can tell the difference in color and taste of soup.

Soup of Udon is usually made from soy source and Dashi(extract of bonito or seaweed). However soy source is rarely added in western region of Japan.

The soup looks dark and it may taste salty when you eat Udon in Tokyo.
It is said that soup is for dumping Udon noodle in eastern region, for dringking up in western region.

In some products ofinstant Udon noodles, you can find "W" or "E", near igredients.
W stands for western Japan, which means the soup is western style. E stands for eastern Japan, which means the soup is dark and soy source based.
If you travel both Tokyo and Osaka, go eat Udon, buy some instant Udon noodles in both places so you can enjoy the different tastes!