I love how each arc really pushes what this manga can do. It's like the manga adapts to fit the genre that is being discussed within. I can see why this is regarded as a classic.
Oh look at me, I can draw a guy smiling while covered in blood, im sure no one has ever done a bloodthirsty assassin before. Let's just slap this baby with some God awful dialogue, add in some cryptic shit, and call it a story. That'll make all the readers satisfied for sure.