drown in the angel’s swamp?
https://www.mangago.me/read-manga/kill_me_now/
https://www.mangago.me/read-manga/tatoe_sekai_ga_owattemo_watashi_wa_kanojo_wo_erabanai/
https://www.mangago.me/read-manga/kitanai_kimi_ga_ichiban_kawaii/ (toxic relationship, features some extreme fetishes such as age regression/babyplay, vomit kink, period blood kink, etc.)
https://www.mangago.me/read-manga/i_m_more_dangerous_than_you/ (age gap, teacher-student relationship but both leads are 18+, bullying and harassment, kidnapping and confinement, domestic violence)
https://www.mangago.me/read-manga/manipulate_my_heart/ (age gap, teacher-student relationship but both leads are 18+, bullying and harassment, kidnapping and confinement, homophobia, human experimentation)
Are there any Yuri/GL manhwas with black flags?