This is the best place to go if you want great Japanese food. They offer everything from sushi to cooked dishes. I've been there probably a dozen times and have never had a bad experience.
The other day I tried their tasting menu for £75pp and it includes a sampling of all their signature dishes, plus sashimi and sushi rolls, and a wonderful dessert platter. For instance, we had a large scallop with a pureed mash; softshell crab and avocado roll; lobster dumblings; raw waygu beef roll; tuna tartare with raw egg an caviar (yum!), a fois gras type roll wrapped in seaweed like a roll but served with a seaweed bread and green plum (divine!); a crab hot-pot; and lamb shops with spicy sauce. They were all absolutely amazing.
The waitstaff are attentive and the food has never been bad. During the summer, they open up the place so even if you sit inside, it feels like you're outside. Plus, Charlotte Street is the in-place to eat these days. A great place to go to impress a client too.