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...
"One night for all signs of civilization to shatter, eh, honey? Onin War."
"انقضى أمرنا في ظرف ليلة واحدة، صحيح يا عزيزتي؟ حرب أونين"
"Unas cuantos salimos a salvo, 
¿cierto, cariño? Guerra de Onin".
"Nossa queda no quarto minguante foi na noite
 de verão, não foi, querida? Guerra Onin."