I am 101% sure that this type of place in Marunouchi would not deny you for being non-Japanese.

Anyway, you should be more adventurous. I can tell you one place where you will be denied for being a gaijin. It's probably 2 km from there in Jinbocho. I don't recall the name. It's supposed to be the oldest sushiya in operation (in the same building). My significant other had been there for lunch with a Japanese colleague. But when we went in the evening and we were not allowed in (place was half empty). When we said in Japanese that we speak some the response was crossed arms. I was relieved because the place looked pretty gross! I don't think historic restaurants (they tend to be grimey) and sushi mix.

I also fully support their right to deny anyone entry, so I don't have a problem with it. However, they cut their potential lunch customer base by 50 people (Japanese) and it may have spread to other company departments.

There are a lot of interesting restaurants in Jinbocho. Some are these old timewarps where tourists would not dare to enter. I went to an unagi place there yesterday for lunch, called Ima Shou (今荘）I hope that I got the second kanji right! Also my favorite high end Japanese restaurant, Den, is in Jinbocho.

Most of these historic restaurants are very welcoming but it is difficult for tourists.