~ bullied/underdog/underestimated -> stronger ~
http://www.mangago.zone/read-manga/the_boxer/
http://www.mangago.zone/read-manga/dear_boy/
http://www.mangago.zone/read-manga/solo_leveling/?60EF -if you haven't read, def reccommend
http://www.mangago.zone/read-manga/weak_hero/
http://www.mangago.zone/read-manga/no_scope/
http://www.mangago.zone/read-manga/geu_kkeute_issneun_geos/?OnwD
http://www.mangago.zone/read-manga/save_me/ -ok, not really but still badass
http://www.mangago.zone/read-manga/boku_no_hero_academia/
http://www.mangago.zone/read-manga/unordinary/
http://www.mangago.zone/read-manga/study_group/
http://www.mangago.zone/read-manga/the_legendary_moonlight_sculptor/?N6iW
http://www.mangago.zone/read-manga/the_second_coming_of_gluttony/?Eldz
http://www.mangago.zone/read-
manga/the_beginning_after_the_end/
some aren't exactly what you described but give off somewhat the same 'vibe' so hope you enjoy~
im really thankful for your suggestions bUT UGH I'VE READ ALL OF THEM AND I WANT TO CRY-
oh lmao sorry~ Σ(っ°Д °;)っ ~I somewhat understand you pain as well T-T
omg dont be sorry pls- it's making me feel bad aAHH-
manhwa or manga where the mc goes through an amazing character development from being in the slumps to being a badass. sort of like super outcast, but i don't want a lot of girls involved. i prefer something with action, non-romantic stories that just focuses on the main character who was maybe bullied until he gradually got stronger. make me squeal from the badass-ness of the action or how savage the mc becomes when he gets stronger. (Like Lookism)
doesn't have to completely fit the criteria, but i'd very much like the character development. (and im thirsty for muscles. my brain is fucked up rn, so pls help me fix it lmao) thankuu