Many are interested in Japan’s pop culture. I imagine this interest led to some people to study Japanese. There are some shops that will meet your needs in the area. You might want to consider sending some items via post instead of carrying them all back to your home.
Bookoff
Bookoff is a used comic books store that provides a wide range of graphic novels spanning the very old to the most recent. Prices begin as low as 100 yen per book. In addition to comic books, Bookoff sells non-anime novels, magazines, CD and DVDs, Blu-rays, etc.
Super Bazaar North Tenjin
North Tenjin 6th/7th fl, 4-30-20 Tenjin, Chuo-ku, Fukuoka City
Business hours: 10:00 am to 9:00 pm
Ohashi Station West Exit Store (very close to NILS)
1-17-1 Ohashi, Minami-ku, Fukuoka City
Business hours: 10:00 am to 10:00 pm
Akiba Sofmap
Sofmap provides a genuine Akiba experience in Fukuoka. In addition to CDs, DVDs, Blu-rays, and figurines, you can find the most comprehensive stock of trading cards and PC games software in Fukuoka.
Bic Camera Tenjin #1 Building B Block 1st/2nd fl
1-25-1 Imaizumi, Chuo-ku, Fukuoka City
Business hours: 12:00 pm to 8:00 pm