Just a quick note to mention that Topps has announced some plans for World Baseball Classic cards for this year. They've already rolled out the first Topps Now WBC cards. Each card is $9.99 on Topps' website but at least the first couple can be found for half that on Ebay. If you're in Japan you can get them on Topps' Japanese site for 1100 yen - they look like the same cards, down to the English text. Obviously we don't know how many cards will be in the set but the 2017 Topps Now WBC set had 64 cards (67 if you count the Spanish language parallels) so I'd expect something roughly comparable.
Topps has also announced some sort of "Global Stars" set but there's no details other than the above photo. The box says it has 20 cards in it - 16 base cards, 2 parallels and 2 inserts. No idea how big the set will be, how much it'll cost (I suspect it will not be cheap), or when it's going to be released.