Gin-san takes history lessons, and teaches you how to hide your porn mags?
Tsukuyo tries to teach Seita history, the subject he's not great at. However, her training (?) methods end up leaving him scarred, which makes desperate Seita ask Gin-san to take over as his tutor...
I'm sure you've hidden a 
porn mag or two before.
لا بدّ أنّه سبق لك إخفاء مجلّة فاضحة أو اثنتين
Seguro que ya has ocultado una 
revista porno o dos en el pasado.
Sei que já escondeu 
revista de mulher pelada.