Ube

Dear All,
i would be going to Japan again this summer and will be staying at Ube for 2 nights. I would like to ask for any suggestions on what to do there or in the vicinity. I have been to Yamaguchi before.
Thank you.
Ps. Is it worth going to Shimonoseki or am I better off going to Kokura for a day trip from Fukuoka?
Thank you.

There's the caves and karst landscape to the north at Akiyoshidai (秋吉台).
http://www.japan-guide.com/e/e6130.html

A bus up to Hagi doesn't take too long.
http://www.japan-guide.com/e/e6150.html

I guess you're going to Fukuoka next? There's not much in either Kokura or Shimonoseki, but of the two, Shimonoseki has a shrine and a hill to overlook the bridge. The miti-no-eki on the north side of the bridge used to have good deep fried fugu (the heat destroys the poison).
http://www.city.shimonoseki.yamaguchi.jp/seisaku/kokusai/gaikoku/top_e...

There's plenty around Fukuoka for day trips that are better.

The most famous site in Ube is Sorinji Temple, due to the temple garden.

Other than that, Ube has Tokiwa Zoo, some museums, other temples and shrines.

You can get a feel for it at the city's official site:
http://ube-kankou.or.jp/sightseeing/

Kokura has a nice castle and grounds, but most importantly it has the TOTO Toilet Museum, which is awesome!!!

I went to a cave in the area, and the landscape on the way there was quite different to anything else I'd seen in Japan. The cave didn't have any spectacular formations but was really long and had a nice walk in the forest.

I had a Japanese friend drive me there so I think it would be not the easiest place to get to via public transport - I went in winter though.
If you hire a car, or if you can work out which bus to catch, there are some really nice beaches and quiet little seaside towns near Munakata.

Or closer to Tenjin there is a little train line which splits from the main Kagoshima line to Saitozaki and you can walk to Shika island which is not really touristy which makes it nice.