Seiri Danshi no Nichijou

The main character, Kirito, had a childhood friend called Hiroaki.
Hiroaki has heavy menstrual cramps and is always full on menstrual days.
Kirito has a light period, so I don't understand why Hiroaki gets frustrated at every period.
Frustrated by the menstrual and emotionally unstable Hiroaki, Kirito just yells at him!

[Taken from Freem!]