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...
Anyway, the Ragnarok I mentioned 
earlier reduced Japan to nothing.
كما قلتُ قبل قليل، أبادت الـ راغناروك اليابان عن بكرة أبيها
Bien, habíamos quedado en que el 
Ragnarok había acabado con Japón.
Enfim, o Ragnarok de que 
falei reduziu o Japão a nada.