Forgotten Title Manga where oblivious boy is raised to be overpowered by Sage and Saintess

So in the manga theres this boy who, from birth, were raised by the two ppl who saved the world and everything, the sage and the saintess (old ppl).

So after he turned into a teen he went to the magic academy, but he was obviously overpowered cuz he was raised by the two strongest people in the world, so he was using ancient runes for random shit, blowing up stuff from simple spell, etcetera.

Thats all I remember, but it should be enough detail, right?
MC gets a girlfriend too, if that matters.

 

Is it the lv 999 Inferior Knight one?

 

Keja no mago probably

 

kenja no mago?

 

probably “Wise Man’s Grandchild” otherwise known as “Kenja No Mago”