Looks to me like the cloth lumbar area on the vertical part of the seat has extra padding underneath it causing it to stick out much further providing better lower back support.

I wonder why they didn't add that to our's?

 

They get extra lumbar support AND cloth seating areas in Japan? Man, they get all the good stuff over there!

Actually, I'd love some more lumbar support.

 

Our leather seats are an option in Japan, these are the stock ones.