Blue Sushi Sake Grill
http://bluesushisakegrill.com/
Blue has grown to enough cities in the US that it can probably be considered a chain. I’m still going to include them on my list because 1) they started in Omaha, so they are at least a Nebraska Chain, 2) their space in the Haymarket is one of the better places to eat in general, but also to eat outside and 3) they do Sushi and food in general really well.