The Concert on the Rock (also known as the 'Surf Rock' Concert) is an annual outdoor one stage event held near Nakatsu in the northern area of Oita Prefecture. The locale is as spectacular as you could ask for - up Mt. Hachimen, next to clear and cooling streams, with a fantastic view over the Nakatsu area... And it is not just the view that keeps you entertained. I think that entry is around the ￥1000 mark. It is definitely worth the trip and the money. A lot of fun.