if you're fine with web novels id srsly recommend omniscient reader's viewpoint. a masterpiece of a novel.
it also has a manwha if you don't like reading web novels ;) (btw the best thing you could ever gaze your eyes upon)
Oyasumi Punpun
Death Sweeper
Three Days of Happiness
Route End
Shokuryou Jinrui
Shokuryou Jinrui Re (sequel to previous one)
Totsukuni no Shoujo
Venus in the Blind Spot
Winter Woods
To You, The Immortal (this one also got an anime)
Bakemono Yawazukushi
20th Century Boys
Inu Yashiki
Uzumaki
Kiichi!!
Kiichi!! VS (sequel to previous one)
Monster (this one also got an anime)
(I can also recommend plenty of anime as well if you want)
I need me a manga webtoon whatever that will make me rethink life please