Monster child...I just finished binged reading that emotional rollercoaster
not sure if this fits what you want, but if it's something sad youre looking for then "a thousand cranes" will without a doubt, give you the feels.
also, "work, fight and love" is certainly a bittersweet one
I think the most painful manga ever is oyasumi punpun
http://www.mangago.zone/read-manga/watashitachi_no_shiawase_na_jikan
Not painful, so much as it is sad
Inoribana
Yup that's the title that made me hurt so much
Someone pls recommend me some painful mangas plssssss. Feel like I haven’t found anything good in forever OTL