By Nishitetsu highway bus to Kurokawa hot spring (about 2 hours 30 minutes)
Ref. : https://www.kyusanko.co.jp/sankobus/toshikan/kurokawa/
●Fukuoka airport (international terminal :platform 2) →Hita bus center→Minamioguniyakuba-mae→Kurokawa hot spring(Get off)
●From Kurokawa hot spring , 10 minutes by car
(There is no public transport from Kurokawa.)
Taxi is available (about ¥1500〜1800)