Yaoi manga

Most BDSM mangas/yaoi involve spanking, so maybe start looking in that area? I dont have any to recommend at the top of my head at the moment

http://www.mangago.me/read-manga/do_do_do_s_kyuu_kareshi/sa/sa-c001/

http://www.mangago.me/read-manga/buji_oni_zeme_seiyoku_zukan/

http://www.mangago.me/read-manga/bousou_kareshi/an/bousou-kareshi-chapter-2.html/1/

http://www.mangago.me/read-manga/nurse_ga_oshigoto/mf/c002/

http://www.mangago.me/read-manga/mayou_otoko/