MC family dead, he quit highschool and works at some freight shipping factory.

He have little sister who quit highschool because some reasons

He works hard and thought he will get promoted but it gone bad, the factory owner introduced a new guy who just graduated from college and promoted him to he position mc desired.

Mc mad, dislike the guy and assault him when the guy talk about his conditions quit high schools and working hard thing.

The little sister then ask mc to attend special schools so they can get high school certifance.

The mc agree, and in the school he meet with this ojou sama who looks rich and she even had this boy companion who seems was her servant.

Mc dislike her because she was rich and think she looks down on people and just playing around.

Mc and the girl got into a fight anyway, mc mock the girl and she then just left.

So what manga is this ?

I think is this one: Chuusotsu Roudousha kara Hajimeru Koukou Seikatsu Roudousha.
I hope I was helpful.

ok thanks it was right