[3] It is characterized by its square shape and flat edges with rather chewy texture,[4][5] and in an authentic sense, ingredients should be from among those local specialties as wheat flour,[6][7] Niboshi dried young sardines to cook broth for soup and dipping sauce.

Originally popularized in the Kagawa Prefecture of Japan, nowadays various types of dashi is applied to the broth outside of Kagawa which varies in strength and flavor across Japan, such as made with more costly Katsuobushi.

[9] It was selected as first place out of 350 commodities in terms of regional branding strength in biennial surveys by Nikkei Research in 2008 and 2010.

[10] Tourists cite udon as both the primary reason for coming to Kagawa prefecture as well as its charm.

[12] Since long ago, quality wheat flour,[13] salt,[14] soy sauce,[15] and dried sardines[15] known locally as 'iriko' have been local specialties of Sanuki Province (now Kagawa Prefecture), which were easy ingredients to obtain for udon.