“We’re busy all the time,” says owner Mark Chen of his cozy Northampton restaurant, which has won Best Of awards for 13 years in a row. Many guests, naturally, are regulars. “These people, they have the menu in their brain now,” he says. But that doesn’t mean there’s not room to grow and change. “Fusion is the key to the sushi menu now,” Chen says. “We have a lot of people who love the fusion menu, like the tomo roll. And the chef [Ken Chen] has been with us since the beginning.” In addition to small parties, Osaka draws large groups and families for hibachi dinners, birthday parties, and special events.