The protagonist is Ralph Esteson. He is a reincarnated person.
He’s always been smart, and he’s also got good ears (h**l ears).
He was reincarnated into another world as a souvenir of his “cheat” and started out as a baby, taking advantage of the ruse of the “world manager” that would have inspired a normal person.
He spent 15 years peacefully in the position of a fallen nobleman. At the age of fifteen, he entered the Royal Academy of Magic and graduated two months later, skipping a grade.
Apparently, it was the “fastest ever” record.
After that, he became an adventurer and spent his time lazing around. He took a prostitute (the heroine) he met in a brothel by chance and made her his wife.