Marunouchi/Otemachi area is the financial city of Tokyo. Not far from the Tokyo station, two areas are located right next to each other with a lot of skyscrapers which are mostly financial institutions such as banks, broker-dealers, and insurance companies.
You may think it is boring to be in the financial city if you are visiting Tokyo for fun but I recommend to stop by at these areas if you are in Tokyo. There are a number of highly-rated, sophisticated restaurants in the area. Marunouchi is also known as a good shopping spot, especially around the Naka-Dori (i.e. Naka street). I think Naka-Dori is one of the most beautiful streets with relaxed atmosphere in Tokyo. Normally, it is not that crowded.
The only time that Naka-Dori becomes packed with people is around the Christmas time when beautiful Christmas lights are decorating the street. The lighting event was canclled during the COVID lockdown but it came back in 2021. Hopefully, we can celebrate the holiday season with gorgeous decorations in 2022.
Marunouchi Terrace (Marunouchi Terrace Building Information | Store information, maps, Parking Lots, etc. | Marunouchi.com) is one of my favorite buildings in Marunocuhi area. It has a lot of good restaurants which are mostly western style such as French, Italian, Spanish, and American. You may find their food interesting as most of the western food in Japan is catered to Japanese taste. If I had not gone to the U.S. and tasted the American food there, I would not have thought American food in Japan is not the real American food that American people would eat. If you are in Japan, it may be worth tasting wetern style food to understand how different it is from your own country’s food. There may be too much Japanese elemnts in it. Or you may find one dish is too small for one person which is often the case if you are in Tokyo.

There are a lot of non-Japanese Asian food options, too in both Marunocuhi and Otemachi areas. I think they are pretty authentic but please let me know what you think!