This questions needs to be asked regardless of whether the story is a Harem or not because even in Harems there is one girl that the Main character prefers over all the others like Rias was for Isse in High School Dxd, and she is the one that controls the Harem.
I want to know who is the Alpha Female of the story that one that controls the others because there has to be someone that he loves above all others.
I especially want to know if the person that he loves the most is his sister in the story because she has the highest affection value of any of the others.