This reminds me of I’ll Parry Everything manga / LN. That character is even more OP. It is weird this has a harem tag. He just had a fan club of men and women.
I read to vol 6 of the LN and there is no romance or harem. Generally all the female students have a crush on the master and the male students madly respect him. I think he does end up adopting Myui Freya. I think he will end up with Lucy Diamond as she is canonically much older (maybe in her...