Technically Ifu is in KandaSakumamachi, but I am associating it with Akihabara since that what most people will look it up under. Ifu is an informal shop about 30 seconds walk away from the south exit of Yodobashi Camera in Akihabara. You walk south-southwest out of the Yodobashi Camera building, past all of the teenagers trading DVDs and around the corner (it's on a diagonal corner lot). It has a long curving counter that goes all the way around the interior of the shop. I ordered the shoyu tsukemen with extra chashu (1000yen). The tsukemen broth was very interesting in that it was very thin and clear (あっさり) and slightly sweeter, but a different kind of sweetness. In the broth were long negi pieces (about 2 inches long and .75 inch in diameter) and chunks of chicken. First time I have seen chicken chunks in tsukemen broth. The noodles were long and very thin and heavy kansui-yellow. A free bowl of rice was offered to me but I didn't accept it as I was getting full already. Many people will put the rice in the remaining tsukemen (or ramen) broth after the noodles have been eaten. Decent if you are at Yodobashi Camera already but the ramen places on the 8th floor are too crowded.
Tabelog entry (more pictures + hours)
Diddlefinger Map (English labels)