OTOH, Yoshizumi hasn't seen any evidence so far of Katou's alleged jealousy, so it probably seems like a harmless enough prank to him

*lightbulb* Fair point -- and something about the way you phrased this made me realize that I'm doing some projecting here: in person, I am way less forthcoming about my emotions than I am online or in correspondence, and a perennial source of aggravation in my life is people who don't believe me when I say I'm happy or angry because I'm not visibly happy or angry enough for them to take it seriously, and then everyone runs for cover when I blow my stack. So that scene makes me want to smack Yoshizumi because it pushes a real-life button. *sigh*

I think you're right about Yoshizumi not meaning any harm - as you say, he truly seems puzzled by how what he's hearing vs. what he's seen isn't adding up, and he's definitely got a reckless, action-before-thought streak (which is perhaps what makes him shine in those samurai roles, and in any case definitely comes to the fore when he puts rescuing the film ahead of self-preservation). And yes, very interesting indeed about Katou's track record when it comes to sizing up character. (And since he's not often wrong, that would make Miyasaka's betrayal even more painful...)