i find this one to be pretty interesting, but heads up, it does have intense sex scenes peppered in there too: http://www.mangago.me/read-manga/the_beast_must_die/?Zhkf
Idk if these are 'extreme' psychological but I read these recently and they were good!
http://www.mangago.me/read-manga/hotel_phryne/
http://www.mangago.me/read-manga/truth_or_dare/?XUBT
http://www.mangago.me/read-manga/criminal_interview/
Ventham
http://www.mangago.me/read-manga/ventham/
Ningen Shikkaku
http://www.mangago.me/read-manga/ningen_shikkaku_itou_junji/
Shin'ai naru Boku e Satsui wo komete
http://www.mangago.me/read-manga/shin_ai_naru_boku_e_satsui_wo_komete/
also nii-chan
http://www.mangago.me/read-manga/nii_chan_harada/
Extremely phycological mangas plzzzzzzz✧*。