He's not last, but because he majors in everything they don't grad him with the other students. If they did he would be at the top of every class.
Not the result, I mean why he's in class 5 instead of class 1?
That's like his homeroom class but he does summoning, swordship, and etc and those are the departments they grade. They grade them by department but not by class and thats which is why atudents are only supposed to pick one. Since he picked them all his grade is treated the same way which is why the teachers want him to transfer fully to one department. Top scorers are picked as the best from the department but prioritizes kids that are fully registered into the department over people registered in multiple. That's why it's accepted his grades are the best and he gets all the privileges of being the top scorer without it being announced (like he's be crowned top student with the best grades of his year without being crowned a "top scorer" its not that he isn’t just the school does not put his grades in with everyone else).
Can someone explain to me why he's in the last class even though he's a top scorer???