The speciality here is ochazuke, a bowl of rice and toppings over which hot tea is poured. Everyone's here for the popular katsuo ochazuke (¥1450), topped with raw katsuo (bonito), a local speciality, marinated in a secret sauce and shredded nori (laver).
Staff recommend eating half the fish and rice before adding the tea, for two different taste experiences (the hot tea will sear the fish). Look for the wooden facade a minute's walk south of JR Kushimoto Station; the tourism association can point you in the right direction.