not sure about underground but Brutal: Satsujin Kansatsukan no Kokuhaku is pretty nice. Not yet completed
https://www.mangago.zone/read-manga/brutal_satsujin_kansatsukan_no_kokuhaku/
Innocent rouge and the squeal
I GOTCHU, i love psychological mangas sm here are some of my favs,
https://www.mangago.zone/read-manga/ajin/
https://www.mangago.zone/read-manga/dead_days/
https://www.mangago.zone/read-manga/record_of_the_dead/
https://www.mangago.zone/read-manga/redrum_327/
https://www.mangago.zone/read-manga/the_cliff/
https://www.mangago.zone/read-manga/distant_sky/ (MY FAVORITE and rarely ever talked abt as far as i know)
https://www.mangago.zone/read-manga/oyasumi_punpun/
https://www.mangago.zone/read-manga/ayeshah_s_secret/
https://www.mangago.zone/read-manga/sweet_home/
https://www.mangago.zone/read-manga/bastard_hwang_youngchan/
https://www.mangago.zone/read-manga/mushihime/
https://www.mangago.zone/read-manga/shiga_hime/
https://www.mangago.zone/read-manga/killing_morph/
https://www.mangago.zone/read-manga/dorohedoro/ (very cool artstyle)
https://www.mangago.zone/read-manga/dark_mortal/ (artstyle isnt very pleasing, BUT THE PLOT IS SO GOOD !!)
Leviathan/ deep water
Tysm (づ￣ ³￣)づ
what are the best, underground gore/psychological mangas/manhwas you've read? I prefer completed works with no bl thanks (▰˘◡˘▰)