Sanuki udon is a popular type of udon originally from Kagawa prefecture in Shikoku Japan. Sanuki is an old name of Kagawa Prefecture. The udon is characterized by its thick, square shape and more tender texture. There are several ways of eating udon. The basic is to choose the temperature: cold or hot in soup. Then there are a lot of choices of toppings and side dishes: eggs, ginger, spring union, dipping sauce, beef, tempura, etc.
There are around 700 udon shops in Kagawa prefecture. Many are family run small shops that only open for a few hours a day until lunch time and/or close on certain days. So if you want to have udon in Kagawa, lunch hour is probably the best. Besides, not all restaurants are served at the table. Many restaurants are self-served which means that you have to go pick your own toppings, side dish, then order udon at the cooking counter. Of course, you would have to clean up (turn tray) as well.
In addition to buying and tasting, you may also try to make some yourself. Nakano Undo School is one of the most famous and popular one.