Wonder of wonders - Ippudo now has tsukemen, at least the one in Ebisu does. What they call Hakata Tsukemen is really just tonkotsu gyoukai. But it was quite good. The default noodle size is 200g and you can get omori 300g for +100yen. Takes 8-10 minutes to cook as the waitstaff will remind you. The taste of the broth was quite like Ryoga in Ookayama, Dai Dai in Jiyugaoka or Matchbo in Shibuya. Very strong age-ninniku and onions taste. Quite good but a touch gritty as you get to the bottom, unless you keep stirring it up. Small chopped up bits of pork, menma and onions. The Ebisu/Meguro area now has another option for tonkotsu gyoukai. Remains to be seen if this is a summer-only thing or not, the below web site says another 6 months.
Read more about it on the Ippudo "What's New" site here.
Ebisu Shop Page + Address
Diddlefinger Map (English labels)