I'm so glad to hear that you are visiting Japan. I really hope you'll have amazing experiences during the trip to Kitakyushu and Shikoku :)
I think Japan-guide is a great site which has a lot of information for foreign visitors to Japan, but also this cite would be helpful for you to customize your travel plan in Kitakyusyu on your preference. This is the Kitakyusyu-city's official travel website written in English. http://www.gururich-kitaq.com/en/
If you like to see/feel Japanese history, it would be fun to visit "Kokura Castle" in Kitakyusyu.The castle was built in 1602 and has 400 history. It has a small museum inside, so you are able to walk in and explore ;)
There is a fun-to-visit market called "Tanga Ichiba" in Kitakyusyu. You'll see many kind of shops sell meat, fish, veggies, sweets, and etc.. in the market. Not many visitors from foreign countries visit this market, but it is an exciting place to feel the vibe of local people and to see/experience the local people's daily-life. This is the market's official website. http://www.tangaichiba.jp/
Sorry couldn't find English ver. and this is written in Japanese but I thought t least you can see what the market is really like by looking through the pictures ;)
well, I'm really not sure whether this is helpful or not, but I'm so glad if it has something to do with your travel. :)
Thank you very much. Have a wonderful trip, Carla!