Sushi Den is one of a handful of restaurants in Denver that never disappoint. I've never had a bad waiter, meal or evening there. And I guess most everyone in Denver agrees, because when I went to Sushi Den one recent Saturday night, the place was packed to the gills. Rather than tread water while we waited for a table, we decided to try Sushi Den's new sibling, Izakaya Den, right across the street. But Izakaya Den is far from an identical twin. In fact, it seems more like a stepsister than a fraternal sibling. It's as open and airy as Sushi Den is compact and frenetic. The architectural style is a somewhat contemporary twist on traditional Japanese, with huge beams, heavy wood and paper light fixtures. The drinking bar (as opposed to the sushi bar) is beautifully made of rattan, and the shelving behind it is red lacquer. Given that quintessentially Japanese setup, I went with the Riki-Sha Martini ($11), made with Absolut Pears vodka, Shochu sake and 7-Up, and sipped it as I sampled a half-dozen items off the menu, each one better than the last. If you want to enjoy the relative calm of Izakaya Den, get there soon — because I predict that with time, this will be another crowded Den.