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...
It led to the "15th Evening 
Treason, the Honno-ji Incident."
هذا ما قاد إلى "خيانة الليلة الخامسة عشر" حادثة هونّو-جي
Eso llevó a la "15° oscura noche de 
deslealtad", el incidente de Honno-ji.
Levou à "15ª Noite da 
Traição", o incidente Honnoji.