The set will contain 53 cards, excluding any secret rares. Although the text on the booster pack is hard to read, it appears the set will focus on Fire, Water, and Dragon-type Pokemon judging by their symbols on the bottom of the booster pack. The booster pack image appears to be final and shows Dragonite, Drampa, and White Kyurem will be featured in the set.
The set appears to have a set code of “6a” rather than “6+,” which may mean it’s a regular mini-set rather than featuring a bunch of reprints like other SM+ sets. The set also won’t feature every card as a reverse holo like SM+ sets, which may be another clue that it will feature new cards. (They print the SM+ sets as reverse holos to make them more “unique,” as in, to give people a reason to buy them. Which isn’t necessary if a set features new cards.)
But that’s not it for new sets! On May 3rd, Japan will also get a Champion Road mini-set. Nothing is known about this set other than it will contain 66 cards and include Blaziken, Feraligatr, and Scizor cards.
As posted a few weeks ago, Japan’s SM6 set is named Forbidden Light and will be released on March 2nd. It will feature Zygarde.