One millimeter thick, seven or eight millimeters wide. A flat udon, and it is eaten right across Aichi prefecture, at home and standing on railway platforms.

Where the name came from is not settled and there are at least three candidates. The strongest is that it derives from goishimen, a Chinese confection shaped like go stones. Another says it comes from kishumen, noodles made by someone from Kishu. A third says it comes from kijimen, pheasant noodles, made with pheasant meat and presented to a domain lord.

The broth, done the old way, is seasoned with dried muro aji and with tamari soy sauce, and it comes out dark and concentrated in a way that surprises people who expect udon broth to be pale. The explanation offered for that is mechanical rather than cultural. A flat noodle has more surface and less body than a round one, so the liquid has to be stronger to register at all.

That is the thing worth holding onto. The shape of the noodle determined the strength of the soup, and not the other way round. These days dashi and ordinary soy sauce are common too. There is curry kishimen, and chikara kishimen, and in summer a cold version called koro. The noodle stays the same and everything around it moves.