Mercari JP, Yahoo Auctions JP and a few others like Rakuten, Surugaya etc. but I find most cards in Yahoo or Mercari.
I think if you make a seperate thread for advice or post it in the general thread you should be able to get helpful replies. A lot of forum members made a trip last year due to World’s so I am sure many will be able to help you out.
You can check out @genchiro thread from last year doing a great job cataloging a lot of the cards in their journey. It is a nice and a latest resource.