My older brother had no idea when I started my period even though I didn't hide it. He never had to act as a parent, of course, but he seemed not to know the average age at all. Takatora may have examined some resources or something, but I could see him not stocking up on sanitary pads in preparation or something like that.

I have friends who have cramps that are so bad they'll sometimes skip school on the first day, one of whom was on birth control for a time despite having no plans whatsoever for sexual activity.

I want so badly to know about the Kureshima parents. Their children are in a locked-down area and the oldest may or not be dead. How important are they to be completely absent now?