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I have been to Fukuoka for a few days and i really enjoyed my time there.
Fukuoka is a bit more international because its close to Korea and it was one of the few citys that had food stalls on the street (along the river) like other Asian countrys do. There´s a pretty big shopping/entertainment complex and quite a few clubs and bars. For cheap but good food i went to the main bus station.
For day/2 day trips i recommend Beppu (the onsen town) and eventually Korea (busan) by ferry (take the fast one).