A shop in Yamagata city called Sakaeya Honten started serving this in 1952. The trigger was a remark from a regular customer: in summer we eat cold soba, so why can we not have cold ramen.

Making it took about a year. The problem was fat. Chill a ramen broth and the fat congeals and sits on the surface in a film, which is unpleasant to look at and worse to drink. The work went into building a broth that would not do that when it was cold.

It is served with ice floating in it, and it is constructed so that the flavor holds as the ice melts rather than thinning away.

It should not be confused with hiyashi chuka, which is a different dish entirely: that has a small quantity of sharply vinegared sauce, while this has the noodles fully submerged in a generous soy-based broth you can drink. The stock here is drawn from beef, katsuobushi, and kombu, with sesame oil added. The shop itself opened in 1932 and it is still there, and the dish spread from that one counter until cold ramen became something Yamagata is known for. Somebody spent a year re-engineering a bowl of noodles for one season of the year, and it is still made the way he settled on.