Kishimen A wide, flat, Japanese wheat noodle. The noodle is traditionally served in (udon) a soup made with soy sauce with deep-fried bean curd, napa cabbage and dried bonito flakes.
The noodle is also sometimes referred to as hirauchi, which means a wide, flattened udon. According to Japan-Brand.com:
The Japanese Agricultural Standards. It is classified as “noodle that is 4.5mm or longer in width, shaped in the form of a band, with a thickness of less than 2.0mm. Only these can be labeled as hoshi (dried) hiramen, hiramen, kishimen or himokawa.” Anything else cannot be called kishimen.
The best source for Kishimen is a local Japanese market if you have one in the area. If not, check other Asian grocery stores with a broad selection. you can also purchase these noodles online at Amazon.com: Kishimen Noodles