Image source: Google Street view
Full name: Seinan Gakuin University Community Center 西南学院大学 西南コミュニティーセンター
Map: https://maps.app.goo.gl/s12b8zhDPNnnTmm5A
Address: 6 Chome-2-92 Nishijin, Sawara Ward, Fukuoka 福岡市早良区西新6-2-92
Directions:
Take the Fukuoka Subway Airport (Kuko) Line to Nishijin Station (station K4)
Exit 7 (stairs) or exit 8 (elevator). Take the side road north (perpendicular to the main street) and walk about 2 or 3 minutes.
Take the 3rd left, and go through the opening in the red brick wall on the corner. Walk onto the campus grounds, and the Seinan Community Center will be on your right.
Be careful going back to Hakata / Airport:
All trains on the Kuko (Airport) line going west will stop at Nishijin. The destination may say Meinohama or Chikuzen Maebaru or something else, but all of them pass through Nishijin.
However, if you are headed back to Hakata going east, be sure the train destination is "Fukuokakuko (Airport)", because about 30% of the trains go to Kaizuka (the blue subway line on the subway route map below). (See this image of the subway platform sign on Instagram.)
Fukuoka subway (underground train) Map source: https://subway.city.fukuoka.lg.jp/eng/route/
* Note: a one-day pass can be purchased for 640 yen. A one-way ticket between the Airport (K13) and Nishijin (K4) costs 320 yen.