this is the only one I'm thinking of atm
https://www.mangago.me/read-manga/lucky_letter/
these r sad too asp
I bawled my eyes out on this one
https://www.mangago.me/read-manga/eyes_clouded_by_the_tiger/
this too
https://www.mangago.me/read-manga/blood_strangers/
not abt death but it's sad like I can't explain it
https://www.mangago.me/read-manga/hanbun_ageru/
this was so sad yet so good for me cause like it's well written I can't put it into words
https://www.mangago.me/read-manga/kimi_no_yoru_ni_fureru/

Please give me your best ghost/any type of death angst bls (ヽ´ω`) long or short doesnt matter