Royal Sushi & Izakaya, in Philadelphia, has an omakase bar that's almost impossible to reserve.

The main dining room, informal and without reservations, serves typical izakaya dishes. Behind it, eight-time James Beard Award-nominated chef Jesse Ito runs the omakase bar, whose 15-course tasting menu changes seasonally, though Ito's nigiri remains a classic.

The $350 omakase menu is the only option at Royal Sushi. Highlights include bibimbap with nori butter rice and a variety of fish, dry-aged fatty tuna nigiri with a hint of Osetra caviar, and live scallop nigiri.

A third of the drop-down menu includes additional options, such as a $32 piece of wagyu or a melt-in-the-mouth A5 Miyazaki ribeye marinated in galbi.

Ito's father, a Japanese sushi chef, prepares the tamago, a sweet egg omelet that puts the finishing touch on an impeccable meal.

The izakaya is dark, sometimes so dark you need your phone's flashlight to read the menu, though the atmosphere is intimate. The back room, with a few izakaya tables, is brighter and quieter. The L-shaped omakase bar seats eight.

Getting a table at the omakase is the hardest reservation in Philadelphia and one of the hardest in the country. It's a good idea to set up a notification on Resy, because last-minute reservations sometimes open up. Those who manage to get a table may be offered the option by the server to make the next reservation, prepaid, for three or four months from now.

If there's no table available in the omakase, the izakaya is still worth a visit. Sitting at the bar and ordering some rolls, like the Bloc Party or the Aka-Taka, is a culinary experience in itself.