This is giving me flashbacks to anime i was interested in where the MC had female students who each became OP in their selected fields and also have a crush on their parental/guardian figure who also happens to be in the same age range as MC here yet they can't beat him despite being the best in their schools.... even the set up here is similar.. that probably explains why after I discovered this I started reading it lol.
The main difference here is that these girls aren't afraid to show affection toward MC while the other one the girls are try and barely make advances... both MCs move to the capital where their students live both MCs are 30+males (kaiser mentioned a character being 22 and there was a 13 year difference.)
Both just happened to train 3 OP female characters one being a sword commander one being strong in magic the other being very smart, and they all have feelings for the MC but they both ignore it or act like they don't understand, both go to the capital gets a job as instructor as well... lol.
But this MC is far more OP but both are loveable characters with how much they love their students/daughters and refuse to step over that boundary, liking this manga so far.
(Sorry for the rant)
Edit: also coincidentally both series have a loli thats the magic instructor and they both immediately recognize the MC and also test them and hire them for magic teacher classes lol.