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...
Hiding books among other books, eh?
إخفاء كتب بين كتب أخرى؟
Escondes libros entre libros, ¿eh?
Escondendo livros 
entre outros livros, é?