@Devil1110f it's only him that has to get so much exp for a level( I think). I think there was a chapter that said he needed more exp because of his class and his system. I think of it as a way to balance him. He's so overpowered that if he were to level up with no restrictions I think he would be stronger than his master. You see he's already a general compared to people his age or that are older than him. Even tho his level may be low he has the strength of at least 20+ levels above him