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...
Who knows what'll happen 
if Sis ever finds these?
ما الذي سيحصل إن عثرت شقيقتي على هذا؟
¿Qué sucederá si Otae las descubre?
O que vai acontecer se
 a irmã encontrar isso?