This Ending
https://www.mangago.me/read-manga/this_ending/
Kaze to ki no Uta (vintage and tragic)
https://www.mangago.me/read-manga/kaze_to_ki_no_uta/
No More Eurydice (not niche but peak)
https://www.mangago.me/read-manga/no_more_eurydice/
https://www.mangago.me/read-manga/the_third_decade_dindin/
It might not be as life changing but I really liked it

yall pls recommend me something emotional and genuinely life changing i beg.. someone niche maybe,..