I mean, while there's no doubt that American comics have had a huge impact on Japanese entertainment as a whole, I don't really "see" it. I mean yes, they're both homicidal clowns that play up the "sadist with a sense of humor" element, and yes the Joker did predate Kefka by /many/ years, and some could even say that Kefka draws many parallels from the Joker in "One Bad Day" scary clowns have been an element of storytelling since...well, since EVER really.
I mean, lets take Steven King's IT for example. Would it be fair to say Pennywise was based on the Joker? What about Beetlejuice? What about Killer Klowns from Outer Space? John Wayne Gaycy? Piemon from Digimon? Alan Gabriel from Big-O? The entire
juggalo community?
emotion_puke
Hell, Bob Kane himself said the joker was largely based on a role portrayed by the late Conrad Veidt from "The Man Who Laughs"
Have fun sleeping...
My point is, ask anyone their opinion of clowns, and 1/5's gonna say they're terrified of them. And that's BEFORE you give them a knife and a taste for murder. It's simply an excellent element to add for a villain, one where you don't even have to
try to make him terrifying, his very presence is enough to induce bedwetting!
...Then again, you could be totally right.