Kawaii Princess iOS Game is free to play with optional add-on content if you like the game and want to support the developer (me ^_^). The content has three new outfits, two new monsters and 1 meteor shower. The meteor shower is an aesthetic that appears behind the moon kingdom. It does not effect gameplay but it is very pretty. The three silhouettes along the top are the new outfits. The middle one might look familiar?? The two silhouettes along the bottom are the monsters. You may recognise one from the card game??
If you choose to get the Galactic Kawaii add-on content, after completing the purchase, head to the customisation screen and tap the ones you want to unlock. Once the two monsters and meteor shower are unlocked they cannot be removed, like the other monsters.