[ yes, this was expected, too, if not welcome. Naturally, Korosensei notices the knife, but he doesn't make any moves to defend himself or disarm the boy. Probably unsurprising, considering how quick his reaction time is. (Though, he thinks to himself, it's not close to what it used to be - but Nagisa doesn't need to know that, now, does he?)

In his prideful opinion, what Nagisa is saying is more attention-worthy than the threat of an imminent assassination attempt, anyway. Mostly because it makes no sense. He's a clever kid, but a straightforward one - Korosensei knows that better than anyone, really. He's not the type to make up an absurd story just to try and catch his teacher off-guard.

Which means that, somehow, he's from a few weeks in the past... Before he can say as much, however, Korosensei has his honor to defend. ]

Nyu? Just what are you insinuating?! I was trying to have a serious moment with you, you know! [ he's the one ruining it, as usual ] Of course I'm the real Korosensei--!! There can only be one! Or do you need to be reminded?