Aww. I don't know why girls hate period - as this manga clearly shows: it helps you get the boy you like, and make friends with your enemies. Sounds quite awesome
Seriously. These chapters make me think back to my own childhood and kids were ruthless. Didn't give af about others feelings or troubles.
"Oh you don't want to talk bad about me even though I talk bad about you? Cool but Im still going to badmouth you."
"Troubled because you got your period? Oh yeah the whole school will know about this freak."
I could go on with the examples. But also where I grew up nobody had real parental figures so that could definitely be part of it lol