Still a fair way's off but I'm plotting out ideas for the fall since I already have my flights in and out booked. Flying into Korea was surprisingly really cheap and I've never been there before, so my thoughts are a week or so in Seoul then fly down for 2 weeks around Kyushu. Been to Japan 3 times previously but haven't gone west of Hiroshima/Shikoku.

Going to a sumo basho is a major bucket-list thing I've wanted to do for years, I'd potentially be willing to go on multiple days if my schedule allows for it. Also some areas I'm looking to get some day hiking in - Yakushima is a definite commitment, I would really like to hike the Kirishima volcanoes as well but it seems like it's had a sizeable exclusion zone for a while now and might be risky to plan around, so my inclination is to try Aho instead.

Are Kagoshima and/or Kumamoto worth dedicating a day to? I've been to a bunch of the original castles so I'm not sure that Kumamoto Castle is a big draw for me, and I don't know a whole lot about what there is in Kagoshima other than the volcano.

Any must-do things on the Eastern end of Kyushu? I greatly prefer small secluded types of onsen towns so I'm skeptical about Beppu (thinking I might daytrip or overnight at Kurokawa). The rest of the east coast seems rather sparse but of course I could be overlooking something significant.

Must-see spots within daytrip range of Fukuoka? I'm primarily interested in the Basho for the city itself, It would be nice to have a day or two in Tokyo before leaving but I'm open to trimming it out if there are worthwhile things to do in the region on those spare days. I know Daizufu is a popular option but don't really know much else about other potential spots that are reasonably easy to access by train.

Any resources for figuring out car rentals? I've never had to sort out renting a car in Japan before but it seems sort of necessary. How big an issue is it getting used to driving left etc?