I was sad to see this; many visitors to the Law & Philosophy Workshop over the last few years enjoyed terrific dinners (and I think conversation!) there.  The menu was eclectic, but the sushi was very good, and the mix of French and Japanese influences on various dishes generally delightful.  Not as fancy (and also not as pricey), but still good for sushi and other familiar Japanese dishes, are the Tsukiji Fish Market and Itto Sushi.

I'll post something in a bit about dining in Chicago, since I often get asked by friends for dining suggestions and I've now been here long enough to have some pretty good recommendations.

UPDATE:  I should mention that many consider Katsu the best Japanese in Chicago–I've never been, as it's on the far north side, closer to Evanston than to Hyde Park!