Responses
According to this page the only people in the Komano family to not be fertile (no viable sperm) was the first generation head and kotarou so far.
http://www.mangago.zone/read-manga/eto_irokoi_zoushi/mi/06bda3bbe9069465bcef0a2204df9b80_chapter-3/22/
Oooooh. I missed that! THANK YOU! ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄
About the issue of Kotarou's family:
So normally the head of the main family, the one being possessed by Koma, must have a child, who will continue the family's duties. But being possessed by Koma lowers their fertility rate so sometimes they are 100% infertile and have to resource to sex with someone of the same sex in order to pass on some spiritual power. And that lover must have a child in order to continue the lineage.
How did they managed to keep it in the family for so long? Adult adoption? Incest? And how the hell is there even a branch family if they have so few children? Btw, Kotarou is very lucky to be born gay considering his circumstances. And why does their partner must be of the same gender as them? Is it about the penetration? The boar did say he would seed Nogi to give him power. But that would mean Nogi would have to bottom for Kotarou and that was not the image I got from that conversation about Kotarou being cute.
I'm confused.