not sleepin

https://www.mangago.zone/read-manga/silver_diamond/
It has 80 chapters..... But, is a manga... So pretty long

silver diamond is actually my fav manga i have all the physical copy. thanks btw! great taste ;)

Idk if you've read this already but it just came to an end,
Though it may not be everyone's cup of tea (I like it):
https://www.mangago.zone/read-manga/form_of_sympathy/

there's one that's ongoing and trust me i dont think its going anywhere anytime soon just unpacking more and more trauma every episode...
https://www.mangago.zone/read-manga/cloud_1/

And now one personal favorites of all time (completed) that 100% hurts me and makes me sob every time I read it, however 10/10 recommend:
https://www.mangago.zone/read-manga/a_proxy_painter/

Again you may have read this, and it dosen't take them 100 chapters per say but it definitely feels like it took them quite the time...really cute though:
https://www.mangago.zone/read-manga/starting_with_a_lie/

This one felt excruciatingly slow too, but I definitely look back at it fondly:
https://www.mangago.zone/read-manga/kisses_x_kiss_x_kisses/

I believe I can sneak this one in too, but almost all the novels by this author can count as slowburn tbh:
https://www.mangago.zone/read-manga/mo_dao_zu_shi_novel/

This one's also ongoing but I think its a slow burn in progress, untill the most recent chapter its hard to even think this would be romance...
https://www.mangago.zone/read-manga/no_moral/

Its a bit hard to remember slow burn gls but the 2 on top of my mind rn are(ongoing by the way):
https://www.mangago.zone/read-manga/tamen_di_gushi/
and
https://www.mangago.zone/read-manga/kill_me_now/

I hope there's atleast one in this list that you haven't read...I'll try to remember more if i can!! my memory is lagging rn T T but Enjoy!! ヾ(❀╹◡╹)ﾉ~

Wow u have the physical copy.... And u read more 4k stories so no wonder u ain't gonna find anything..... What abt this...
https://www.mangago.zone/read-manga/koori_no_mamono_no_monogatari/
This one is from the same author....