1. He spend most of his time in the library to read books and research things. He is satisfied in meeting the minimum requirements of the curriculum so he mostly do not attend classes.
2. Upon attending classes for the first time, he had an unusual way of talking towards other people, which made them irritated.
3. A woman confronts him, but his unfazed demeanor, combined with his unusual way of talking and answering questions, made the woman burst out of anger that she did grab his book and throw it away.
4. He tends to hide his powers as the academy's headmaster requested, but when the same woman declares to have a fight with him after school, he single-handedly countered her magic, which led her dumbfounded. Much less to a shocking state after the headmaster revealed her his license identity.
5. And so on...

Part one, boy excels at magic but the world is in a crisis, so the military takes notice of the boy's talents and turns him into a bloody killing machine (Fruit of grisaia anyone??)

Part two, the boy starts to get sick of either seeing comrades die or tires of killing constantly without end

Part three, boy wishes to retire but the boy's CO panics at such statement that CO plans everything in his power to get the boy either tied to the country through a means of love or through a means of force, due to this, the boy is FORCED to go to school, which he didn't want to go to in the first place and just wanted to study magic.

Part four, boy knows he will get s*** on due to being too OP so he tries to hide his powers. Little did he guess that there's a lot of stuck up pricks in his school where the CO obviously planned in as well.

Part five, when his favourite pass time gets ruined, boy goes and implants fear to ensure previous event won't happen again, then again CO swoops in and spoils it by showing his OP stats.

Final statement, to be honest, if I was that boy as well, I wouldn't want to continue killing endlessly because it does take a toll on a said person. Second, I'd totally do the same thing if I was this boy's CO, such an asset being retired while majority of the world is still under monster control is unacceptable in this case but, the boy was turned into a killing machine at the tender age of SIX like my god child rights, then again, doesn't really matter in that crisis.I would do EVERY SINGLE TRICK IN THE GOD DAMN BOOK just to make sure that boy will keep fighting, because I would want to reclaim the land that was lost as well as increase land for future development and weapons. All in all, the aspects are good, just a slight bit rushed if some people can take it that way.