Best way to get here

I would like to visit the Kamikaze Museum in Chiran (1 day, including travel from and back to Kumamoto. Sat April 5).
Using the JR Pass, how do I get from Kumamoto to Chiran?

. . . is pretty interesting. They have a Zero on display that was shot down and pulled out of the water. I visited the museum as part of a bus tour of the peninsula that departed from Kagoshima.

However I don't think there is any train station near the museum (nor in Chiran), and it's a long train ride from Kumamoto. Even visiting the museum from nearby Kagoshima would be difficult without a rental car. There might be a bus to the museum from Kagoshima. You can't do it in one day from Kumamoto.