The MC, a campus student, has a unique system that allows him to gain harem members, servants, workers, and offspring through copulation. This is because his system requires strategic thinking and the formation of subfactions.
His smartest companion is his girlfriend, who helps him navigate the system's complexities.
Within the first hundred chapters, most of the surviving women who didn't die from sickness became part of his harem, excluding those who were fat or unattractive, as he is selective.
This includes MILFs, teachers, mothers (with their children, if they have one, becoming part of the fortress), college students, soldiers (military), shop owners and any and all women.
Through skills bestowment, MC can grant anyone skills, both male and female, though for him, it's selective to whom he bestows it to.