Brutal Sex

How about Love Prism? Its pretty hardcore.

http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/mh/v01/c001/2/

http://www.mangago.zone/read-manga/gintama_dj_get_me_out/ (gintama doujinshi+gangbang

http://www.mangago.zone/read-manga/haitoku_no_niwa/

http://www.mangago.zone/read-manga/kobi_no_kyoujin/

You can also check these lists :
http://www.mangago.zone/home/mangalist/28457/?filter=&page=1

http://www.mangago.zone/home/mangalist/28292/

try this :
http://www.mangago.zone/read-manga/under_grand_hotel/
http://www.mangago.zone/read-manga/pet_keiyaku/
http://www.mangago.zone/read-manga/kinbaku/
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_asobikata/ (series)
http://www.mangago.zone/read-manga/m_nano_baka_nano_hentai_nano/
http://www.mangago.zone/read-manga/mizugi_tte_kimochi_ii_ne/ (one shot shota)

http://www.mangago.zone/read-manga/prisoner_kaen/

http://www.mangago.zone/read-manga/fate_zero_dj_fuck_ero/

http://www.mangago.zone/read-manga/eien_ni_owaranai/

http://www.mangago.zone/read-manga/mob_for_jack/

http://www.mangago.zone/read-manga/itou_san_kuraka_sui/

http://www.mangago.zone/read-manga/zankoku_na_kami_ga_shihai_suru/

http://www.mangago.zone/read-manga/gamushara_mob_rape_2_chikan_jigoku_hen_kuroko_no_basuke_dj/
(づ￣ ³￣)づ