Wheat flour is kneaded with water, rested, rolled thin, then torn by hand into the simmering pot. That last action is the name. Hittsumi comes from hittsumamu, the local word for tearing something with your fingers, so the dish is called after the gesture that makes it rather than after what it contains.

Along the Kitakami river there were years when cold summers meant no rice. Barley, wheat, and buckwheat were grown against that, and a whole family of dishes developed around wetting flour and working it by hand. The regional term for them is shitonemono. Hittsumi is the one that stayed.

It has other names depending on where you stand: tottenage, hatto, kiribatto. The broth and the contents vary too. Chicken, mushrooms, river crab, whatever the valley had. There is no canonical version and nobody appears to want one.

That plurality is the thing worth noticing. A dish with one name has usually been written down by somebody. A dish with four names, cooked four ways, has passed through a very large number of kitchens without ever being standardized. It gets made when people gather for farm work, at local events, and on cold nights, which is most of them here.