@TNT261
Pretty sure it was explained at one point (though considering how slow this manga is about it's updates, it could have been literally half a year ago or more) that he is hiding his ability and identity for a few reasons, one of which is to see the progress of magic and how his family has lived up to his teachings, had he revealed his ability earlier, it's likely that many things would have been hidden from him, not to mention his father would have tried to use him, even taking his mother as a hostage, which is probably the reason he hid it from everyone up to this point, that said seeing his brother probably killed by his father most likely made him snap and stop giving a damn anymore.
Keep in mind, he's not a decendant of ephtal, he IS ephtal, and using magics of what was borderline considered a demi-god in the manga's world would have major, global consequences that he would be well aware of considering his actual age.
@TNT261 reasons to hide the power, simple, till you get a good lay of the land, it's better to be hidden then go balls out and have many loose ends that can be used against you. unless you are capable of properly securing your loose ends, hide till you can or they are gone.
His main reason to want to show magic off, get into magic school and learn more, was crushed by the piss poor development of magic and how things that use to be average are legend, so if that's the case, why show anything if no one can help you advance anyway?
I can't imagine any good continuation to this. Either he says fuck it and stays annoyingly OP, or regrets going all out and goes back to hiding like a bitch.
good thing he didn't pussy out on the killing though i'm willing to bet somehow his father and/or his brother ends up surviving and revealing his power making him the nr 1 enemy of the world or something like that.
@TNT261 pretty sure someone using level 10 magic is going to get her attention though. Though since the girl on the cover is most likely Merlin, it isn't so much not having got to her, but not having gotten back to her.