JUN

How would they be main character if they’re side characters?

um maybe https://www.mangago.zone/read-manga/omniscient_reader_s_viewpoint/

it's a thing! sometimes the story is about how much the side character mc hates their world or them being reincarnated into a bl world AS a side character and then living in the new world

it's a genre that makes sense i swear

ohh now i get what u mean there are plenty of stories like this

https://www.mangago.zone/read-manga/i_became_the_lousy_side_top_official/ maybe?

YES THANK U I LOVE SIDE CHARACTERS WHO TURN INTO LEADS MWAH<3

Someone hold my hat
Most of these are it! (Some are slightly different but with the same concept)

https://www.mangago.zone/read-manga/bl_game_no_shujinkou_no_otouto_de_aru_koto_ni_ki_ga_tsukimashita/

https://www.mangago.zone/read-manga/zettai_bl_ni_naru_sekai_vs_zettai_bl_ni_naritakunai_otoko/

https://www.mangago.zone/read-manga/100_ways_to_seduce_the_villain/

https://www.mangago.zone/read-manga/to_deny_the_route/

https://www.mangago.zone/read-manga/stuck_in_my_sister_s_dating_sim/

https://www.mangago.zone/read-manga/i_took_a_trip_to_an_otome_game/

https://www.mangago.zone/read-manga/summoning_a_bl_fan_to_another_world/

https://www.mangago.zone/read-manga/single_not_ready_to_mingle/

https://www.mangago.zone/read-manga/reincarnated_into_demon_king_evelogia_s_world/

isekai BL:
https://www.mangago.zone/read-manga/the_affairs_of_the_other_world_depend_on_the_corporate_slave/

https://www.mangago.zone/read-manga/kiss_the_abyss/

this is like BL reincarnation:
https://www.mangago.zone/read-manga/turning/

https://www.mangago.zone/read-manga/monochrome_rumor/