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...
So, once the country lost its rulers,
وهكذا، بعدما فقدت الدولة حكّامها
Entonces, cuando el país perdió sus líderes, 
aparecieron generales Sengoku por doquier,
Quando o país perdeu seus governantes,