It's a bl the mc falls in love at first sight with professor of another department/uni and changes his subject,the ml is also a heir to some big shot but illegitimate (maybe) and his other brother has dated or been with mc in his school days, they have a 1 night stand then starts dating maybe .
???
Any suggestions for black flag or similar to heat stroke
some black flags for you.
https://www.mangago.me/read-manga/no_better_than_strangers/ (about the boss side story)
https://www.mangago.me/read-manga/even_if_you_don_t_love_me/
https://www.mangago.me/read-manga/sadistic_beauty_bl_sidestory/
https://www.mangago.me/read-manga/wish_you_all_the_best/ (he reforms but still)
Thank you so much