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...
He figured Hideyoshi must've been 
wasting time on his backside,
تبادر إلى ذهنه أنّ هيديوشي ربما كان يقضي وقته عبثاً جالساً عليهما
Supuso que Hideyoshi había estado 
perdiendo el tiempo a sus espaldas
Ele imaginou que Hideyoshi
 estava sentada nelas,