mc who are growing his place/dungeon/faith/land/people

mc is a game developer who transmigrated into a villain, who's a mage, noble and a head professor of a big fancy school. there is romance, clearly, cuz the villain has a fiancé. idk what's heading but mc did find her cute? mc also had a ex. which idk.
its pretty good read. before I got spoiled about the romance thing. growing his power, idk if anything
spoiler:



I read some comments, they said that in the novel, it was a harem. so. idk if the manga going that direction or not. likely I guess.