Otemachi, Marunouchi, Nihonbashi, Tokyo, and Kanda will tide you over if you need ideas for lunch or dinner.
But for now, let's party! Several weeks ago, Shaft and I entered into a long process of negotiation that ended up with us having lunch today. She finished her pre-lunch meeting and off we went - I had booked Yoshiki, and a good job of it, because it's the highest-rated non-ridiculous sushi 'joint' in the area that's open for lunch. It never ceases to amuse me how foreign writers love to say 'sushi joint', even when paying $100+ for their sushi. It also never ceases to amuse me to make vague and unamusing jokes about foreign writers, like my writing is somehow better. You know what this picture shows? Yes. The sign and stairs. It's right across from the Mandarin, and would actually be a good option if you were staying there.
similarly-priced one that I was embarassed to take Victorious to in Asakusa.