I didn't notice before but this has the Superhero tag now. So the latest "generation" is killing the men too? I'd have thought they'll keep them around as breeding stock, but if it becomes standard practice to kill the men after reproducing they'll... eventually run out of men. Well, I suppose without the intelligence of SBGs like Sara and Cherry to guide them they'll do dumb stuff like this.
I'm more surprised that a side ship seems to be getting teased in a harem manga. This is mildly interesting because this seems to break an unwritten rule or two in harems: all the girls must be love interests for the protagonist only. Well, unless this kid gets killed off at some point. If a side ship happens that would be unusual, but I know some readers are bound to call that "NTR" even though Ichiyoshi refuses to get into a relationship with anyone.