Tongarashi is a small little soba and udon with tempura shop that is run by an old couple. One thing that really sticks out about this place is the prices. Most of the meals were about 350-400yen for a huge bowl of noodles of your choice with tempura of your choice. And even with the price so low, it was really filling, so filling that I couldn't finish. The shop mainly consisted of only salary-men who were lined up through the shop for this great deal. There was always a line the whole time I was there and I can definitely see why.
The whole area around this shop is filled with restaurants that I can understand how hard it would be to choose one for a visitor, and this one is quite a find. The prices are amazing for this high quality meal. While it's probably not worth it to make a special trip to this restaurant, if you're in the area (say for example seeing Koishikawa Korakuen Gardens), it's a pretty good spot for a quick meal.