Yoichi
The originating restaurant of 'Ryukyu', Oita's local specialty — fresh fish (yellowtail or horse mackerel) marinated in a soy-mirin-sesame tare and served over rice. Long operated as 'Nidaime Yoichi', now continues as 'Yoichi' after relocation. This fishermen's meal-turned-local-classic starts at 1,800 yen. Only 8 counter seats, also serves premium Seki brand fish. Tabelog 3.68, 154 reviews.
Reviews highlight 'the original ryukyu-don is here', 'the fresh marinated local fish is exceptional', 'a must-visit in Oita'. 154 Tabelog reviews, Tabelog 3.68. Repeat visitors from afar as well as locals. No PR elements. Yahoo! Map 3.89 (26 reviews).