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...
If I recall correctly, they got their 
hands on some overpowered technology,
إن لم تخنّي الذاكرة، تمكّنوا من الحصول على تقنية مستقبلية فائقة التطوّر
Si mal no recuerdo, se toparon 
con tecnología superfuturista,
Se eu bem me lembro, eles conseguiram
 uma tecnologia hiperfuturística,