Huiray, the pack of noodles I used does say "mugi", but it doesn't actually mean buckwheat (just to be confusing!) It's a retro sort of name, where "mugi" is a catch-all word for almost any kind of grain other than rice that is used for flour.
Chris, the appeal of "tsuke-men" is probably the fact that it brings ramen closer to other types of cold noodles served in Japan. Hiyashi chuuka or chilled Chinese noodles (= ramen noodles) is a popular summer dish, but it has a real Showa feel to it, with all those '60s foods like cucumber, ham, tomatoes...and the dip is a bit sweet-sour.
Tsuke-men is more straightforwardly savory, with the dipping sauce just a concentrated version of ramen soup, served hot or cold, as you like. A big bowl of ramen is hot, so it takes a while to eat, yet needs to be eaten as soon as it's served, so that the noodles don't go soft, and of course it's steamy and heavy in summer. Hiyashi-chuuka is chilled, but tsuke-men is served at room temperature - which is the default for Japanese food anyway. It's more adaptable when you are eating with friends.
It is well worth giving the noodles a working over as you rinse them, so that they don't stick together when served.
Images of tsuke-men with dipping sauce. As you can see, there are all kinds of dip. You just pick up a few noodles, dip them in the soup, and eat, occasionally fishing some meat or vegetables out of the dip to vary things. Including meat, tofu, or vegetables in the dip is quite common with somen or hiya-mugi as well, especially when eaten at home.
