Why it's Never Let Evil Take Root, featuring a patriotic and self-sacrificing 17-year-old protagonist who saves his homeland from being taken over by a Bolshevik who had just praised the genocidal tyrant ruling across the sea with a single, highly public act of heroism. I do believe he's one of the most inspirational characters of early animes from the 1960s.

(The joke refers to this guy. And yes, the dude getting stabbed was indeed a big fan of Chairman Mao, to the point where even his fellow Communists were uncomfortable)