Don't Spoil Me, Maid Boy

The infamous heiress of the Hachinomiya family, Mitsu, is a girl who longs for a normal youth. After being expelled from a prestigious school, she decides to start over and transfers to a new school, only to find it to be a den of delinquents. There, she meets Kitamura Sumire, the most notorious delinquent at school, who says, "I am your servant." Sumire begins to serve and pamper her with all his heart. How will Mitsu’s new life unfold...? (Source, Kodansha, translated)