There are those who have a fetish about menstrual pads, yes even used ones. (I don't understand it myself.)
I'm not entirely sure this is a guy though, it might be a girl. The source link gives a 403 forbidden now so I guess we'll just have to guess about it.
It's not used if it's closed up like that. I have the idea that that is a guy holding the pad, imagining giving it to the girl. God only knows what will happen next.
Apparently has to do with the him secretly digging the contents of the pink pouch Hagio is holding and recalling her mentioning that the contents are a girl's secret.