This is a tiny hole in the wall that often goes unnoticed by casual lookers. It almost disappears in between its neighbors on Newbury Street and can hardly be considered a swanky establishment like other restaurants on that street. However, you'll be happy to know that it's possibly the best value around. Pieces of sushi are around $1 apiece and is surprisingly good. They're pretty fast, and you won't pay through the nose.
The one major downside is that the place is tiny. Waiting for a seat is extremely common, and you won't be seated at your own table. However, if you're really pressed for time, then you can just order takeout.