If you want a slightly funky, unconventional, high-end sushi experience, why not head over to the hump in the Marunouchi area. You'll enjoy the view, atmosphere, and the food for a moderate price.
the hump is found on the second floor of the Meiji Yasuda Seimei building (otherwise known as Marunouchi My Plaza). Since most of the restaurants are in the basement, on the restaurant floors, this is a bit secluded and hidden. Inside, it has a lounge-like atmosphere, dimly lit with modern furniture. From their large windows, you can see the Imperial Palace right across the road. At first glance, you would not know this is a sushi restaurant. But sure enough, in the back, there's a counter and itamae squeezing some sushi.
the hump was originally a sushi restaurant in Santa Monica, in a private heliport, serving to only select customers. They opened a restaurant here in Marunouchi and serve to the Japanese crowd, traditional edomae sushi as well as California style rolls. The sushi is good. That you're not sitting right in front of the itamae-san and ordering from him does not lower the quality. The fish is fresh and delicious, of the standard you'd expect from the Marunouchi area. The pieces are shockingly small though (or kawaii, depending on your viewpoint), even for Japanese standards. I ordered the naminigiri from the edomae sushi section of the menu which was 8 pieces of standard nigiri for 2950yen. If you're going there to stuff yourself, well, first of all, I wouldn't recommend sushi. Second of all, this place is especially small portions -- I suggest ordering more than you would normally. I did not get a chance to try any of the rolls, so unfortunately, I cannot comment on those.
Overall, I loved the experience. It was a chance to eat sushi in a very foreign atmosphere in Japan. I would suggest maybe coming here on a date, perhaps. There's a bar that's open late, so it's good for dinner and some drinks afterwards as well.