This is how I think it went: The mc has to join some club at his high school, and so he joins one that will be easy. It turns out that the club is run by a delinquent that will fight off anyone who joins because he wants the club room to himself (to nap I think) and he will become the underling(?) of the person who can beat him. Though some accident, the mc beats him and people in the school start to revere him for finally beating the club room boy. The two become friends, and eventually lovers.

Somehow I think mc's brother was involved, like the boy in the club was in love him (?) or that the brother was also apart of the 'club'.

[img]https://www.mangaupdates.com/image/i96583.png[/img]
Rush!
by Yukimura

Found it using the genre "yaoi" and tag "Delinquent/s" in the Baka-Updates advanced search.

Thank you so much!