Renting a car around Kyushu?

Hello! Looking for some advice. I’m thinking of renting a car while I travel around Kyushu, because it would faster than bussing. Some areas I want to wander around are rural, and it would be nice to not worry about missing a bus. But I’m going by myself! Any recommendations of car rental places or general ideas of how much it should cost? I’ll be hostel jumping so I’m kinda hoping I’ll meet other travelers along the way that I can offer rides to in exchange for some gas money. Can I ferry to Yakushima with a car?

by sar_racha