O-Ei-san
Founded around 1955, this beloved Chinese diner has been a Sasebo institution for 70 years. Famous for staying open until 3 AM, it's the city's go-to spot for a late-night meal after drinking. All dishes are under 1,000 yen — champon, sara-udon, ramen, and fried rice with pickled mustard greens. Ranked 34th among 507 Sasebo restaurants on TripAdvisor (4.3/5).
Many regulars report visiting for over 10 years. The straightforward, traditional champon is praised for its 'unchanging deliciousness.' The pickled mustard green fried rice has fans who say 'this is the only place I can get it.' Open until 3 AM, it draws a steady crowd of late-night diners.