@tanooki He was raised as a female until he took over from his father, which when he was 14 and iirc the cursed only took over his body when he took over the demon hunters organization, that time he either already married to Amane and manage to get 5 children or just started to build his own family. By the looks of all of his children, I do think what
@stal2walk said is correct. The first 2 dead sister is twin, while the three surviving children are triplet with the heir with only 1 or 2 years difference in age with the twin sister. I think only when he gets the heir to the family when he decides to learn sword fighting. Coz Amane was by his side on that panel.
Why am I discussing about how a man build his family though lol
What I'm worried now, who is going to help Tomoyo San, now that Rock Pillar decided to fight UM1?