This place does not appear to be all that well-known, at least not outside of this area, however it was recently featured in an issue of Otona No Shumatsu. It's located in an out-of-the-way area in Shinkawa, near Kayabacho station on the Hibiya-sen. You leave the station and cross over the river going southeast, past a nice set of cherry trees on your right. This place is almost certainly not related to the main Taishoken ramen chain, there seems to be a lower-tier of Chinese restaurants throughout Tokyo that are named Taishoken but are not related to the chain (or to each other), and this is one of them. They seem to be primarily famous for a liver-and-vegetable rice bowl. What I went there for, was my secret weakness "suratanmen", hot-and-sour soup with noodles in it. This soup had various vegetables in it, some chicken and beef stock, and then a very thick layer of fat and ra-yu (spicy red oil) on top. Lots of vinegar too. They have a wide ranging menu of many Chinese soup favorites. They seem to be moderately known for the liver and the suratanmen (that they actually call su-ramen, "すーらーめん"), you can see them both on the board out front. I thought the su-ramen was decent, perhaps a bit on the hot side, I like to get my suratanmen taste from a balance of ra-yu, pepper and vinegar + pork, and the pork was kind of skimpy too. Good but not quite worth a special trip. Nice home page though. I also have to say quite fairly-priced for the volume too.
Shop home page (better pics)
Diddlefinger Map (English labels)