Rental car, Takachiho, Oita, Aso, Kumamoto

Hi there.
I wanted to see Takachiho along my visit to Japan and Kyushu in a few months but a bit hard to plan on how to travel and where to rent the car.

I know transportation to Aso, Takachiho, etc, exist but going by rental car is probably more convenient.

However I do I seem to need to drop the car off in a different prefecture, meaning a higher rate in the end, compared to backtracking and going from there onwards.

I am not aware of how fast it would take to travel on the roads either, and considering the condition after the Kumamoto earthquake.

Any suggestions or ideas?

Start off in Kumamoto or Oita or Beppu?

I don't know your detailed itinerary, so its harder to give good advice, but when I went to southern Kyushu last summer, I rented a car in Kagoshima and dropped it off in Miyazaki. Having a different drop off point is more expensive, but I didn't even consider public transportation. For one, I HATE buses, especially for long trips, but two, if you want to see Takachiho to its fullest, the only way is with rental car OR staying the night (or both). The night dances are from (I think) 8-9, so unless you stay over at night, you aren't going to get to see them if you have to catch the last bus to somewhere. But in general, public transport in that area is minimal and rental car is the most flexible option. I like flexible so I always rent a car if I can help it :)

However, I don't know the condition of the roads around Aso well. We drove from Kagoshima up through Kumamoto to visit the castle, then across Mt. Aso to Takachiho, then down, but I don't know about that route now. You'd have to check. But a car gives you the flexibility to take a different route, so I'd still recommend it.