Finally I went to Manyo-no-yu(hot springs) the other day.
It's close to the Fukuoka airport.
They have some family hot springs(private), Ganbanyoku, a large relaxing room, a internet room, a hot yoga studio and more!!!!!!
You can wear Yukata(spa gown) for free!!
There are free shuttle buses from Hakataza(5 min on foot from Fukuoka Hana Hostel), Hakata Sta and Fukuoka city hall in Tenjin.
It was pretty good place!!