Dark Heaven... literally about everything you asked for~~~
http://www.mangago.zone/read-manga/my_broken_mariko/
after effects of suicide
http://www.mangago.zone/read-manga/boys_run_the_riot/
transgender boy struggling with acceptance
http://www.mangago.zone/read-manga/suicide_boy/?RoEn
dark comedy, but does cover some serious subjects
http://www.mangago.zone/read-manga/nii_chan_harada/
child grooming, painful but realistic
http://www.mangago.zone/read-manga/ao_no_flag/
Tackles homophobia and sexism. HIGHLY Recommend.
http://www.mangago.zone/read-manga/shimanami_tasogare/
Tackles Self acceptance and homophobia. Theres also a trans character which is some nice representation to see
http://www.mangago.zone/read-manga/pandora_s_choice/
Tackles racism and misogyny
http://www.mangago.zone/read-manga/chichi_kogusa/
This ones pretty good too- its abt being a single parent and dealing with loss
Mangas that are realistic could include mental illness, racism/poc issues, homophobia and/or people just trying to find themselves