Sauce Katsudon Kiraku
Founded 1928 – nearly 100 years old. Recognised by locals as the birthplace of Komagane sauce katsudon. House secret sweet-savory sauce passed down from the founding generation. Local Koshihikari rice. 46 seats (30 table + 16 tatami). Tabelog 3.47/236 reviews. TripAdvisor Komagane 4.4/13. Fills up before opening. Cash only.
Reviews: 'The true original', 'Authentic taste unchanged since 1928', 'The sweet-savory sauce balance is perfect', 'Every local knows this place', 'Lines before 11am opening – full within 30 minutes'. Listed on Komagane Tourism Association official site. TripAdvisor 4.4.