It is an excellent novel, it has a good development of characters, world and the ways in which it obtains the girls from the harem is going well in comparison to other novels, what I would add would be more slices of life adding dates or moments with the heroines or some moments training with the heroines or alone, it doesn't have to be dating or outside the academy, it could be moments of the mc chatting with the girls he already has or joking with them, just extend a few moments, that would add more life to the characters.
This has potential, it would only lack those small details and a more frequent update and it would easily scale
Story development 10/10
Character development: 10/10
World Development 10/10
Romance 8/10