Each Japanese Transformation Mask Booster Pack contrains 5 random cards each.

Mask of Change, launched on April 26, 2024, is the sixth main expansion in Japan for the Scarlet & Violet Pokémon TCG series. When combined with Crimson Haze, it mirrors the content of the English set Twilight Masquerade.
 
Just like its companion set, Mask of Change is themed around Kitakami—the region featured in the Teal Mask DLC for Pokémon Scarlet and Violet. This time, though, the spotlight is on Ogerpon, the legendary Pokémon behind the Teal Mask. She’s celebrated with four Special Art Rare cards, each representing one of her distinct masks. You’ll also find charming card artwork of Pokémon helping prepare for the Festival of Masks, a fun nod to the DLC’s storyline and Kitakami’s folklore.