Have you read any Junji Ito’s works?
there also this manga that i think has semi kinda sorta same vibe with the summer hikaru died (i also love this manga btw) but it’s ongoing
https://www.mangago.zone/read-manga/otsukaresamakurose_kun/
also this one (also ongoing sadly)
https://www.mangago.zone/read-manga/koisuru_psycho_no_shirayuki_kun/
https://www.mangago.zone/read-manga/shin_ai_naru_boku_e_satsui_wo_komete/
https://www.mangago.zone/read-manga/mysterious_village/
https://www.mangago.zone/read-manga/juujika_no_rokunin/
the first one is my absolute favvv, but the last two r still ongoing sorry!
Psychological/horror manga recommends??
Possibly shorts and complete
(If it can help, some that i like are another / the summer hikaru died / takopi’s original sin..)