Comments of chapter undefined of High School Chronicles: The Otherworldly Harem[Dropped]

So, even after all the "lucky" events happening around him, wasn't he able to at least suppose that he is related to them. Did his intelligence decrease to add drama? Why was he described to be smart in the former chapters?

why are life long friends introducing themselves in school at 18 years old after knowing each other since elementary age❓🤔