So I remember reading a book or 2 as I don't remember if they are the same one or not so im going to treat them as 2 separate books.
So the first one is the kid starts to learn his parents magic without them knowing, mainly water magic, and when they do learn about it they arrange for a teacher for him.
The second one is the kid goes out into a forest and stumbles upon a guy who he takes as his master and he starts to teach him magic. As his graduation and final lesson from his teacher he is to purify his teacher, as he learned he is a undead or ghost. I believe that later on he ends up going to a school and meets friends and they have to do missions together or something like that.