Worstgen
Light D Lamperouge
https://punpun.fandom.com/wiki/Pegasus
Uncle Van
As Light said, it's from Oyasumi/Goodnight Punpun. Their styles are similar.
I'mTired
Thanks, so it's Oyasumi Punpun, I've been avoiding it for a long time, just can't find the right time to handle the heavy atmosphere from that manga. I should really pick it up soon.
Uncle Van
The author's name is Inio Asano. If his 150 chapter manga is too much, you can start off with his smaller works to get a feel for his style. Others are around 20 to 30 chapters with similar tone.