I would simply say, Hiyashi Chuka, is a style of cold ramen topped with vegetables and ham. It is a seasonal food evoking the coming of the Japanese summer, in fact you can find many adverts and shop flags advertising their “冷やし中華始めました” which means “ We have now started serving Hiyashi Chuka”.
I am sure that you already love Japanese ramen, but I also think many foreigners haven’t tried Hiyashi Chuka yet. Why don’t you try Hiyashi Chuka it and come feel the Japanese summer?