Saikyou Ni Uzai Kanojo No, Asu Kara Tsukaeru Mount Lesson summary:

Mount! is the ultimate ranking method that has been passed down since ancient times.At Saginomiya Academy, a private school for children of the upper class, there is an absolute rule: It is to take mount and win!Rei Satou, who is the very definition of average, is destined to be in the lowest class. Where he will spend three years being bullied by the rich. At this point, the only way to survive is to rise to the S class. But before his shocked eyes, a beautiful stranger suddenly appears. Tsukinami Senri kisses him out of the blue and says,"Let's be lovers and take the happiness mount!" "How come?!"Team up with the most annoying girlfriend and aim for the top of the school!