Kirk here. Recently, William mention the new Kyushu Chuo Expressway. I missed it at the time but it seems to have opened in February. Eventually, it will allow people to get from Kumamoto City to Nobeoka in Miyazaki Prefecture. Currently, however, it makes a trip to Yamato (previously known as Yabe, where Tsujunkyo is) much easier. Here’s a YouTube video (from which the screenshot was taken) about the opening:
https://www.youtube.com/watch?v=bVEVwQ7sQA8
Here’s a Wikipedia page in English:
https://en.wikipedia.org/wiki/Kyushu_Ch%C5%AB%C5%8D_Expressway
It’s a little out of date but presents the basics.