In the Pokémon game, Rare Candy can be used to increase the level of a Pocket Monster. In Japan, you can buy Rare Candy ("fushigi na ame" or ふしぎなアメ) at Pokémon Centers across the country. But, bad news...
As the candy's label clearly states, "Even if you eat the candy, you will not raise your Level. Leveling up is dependent on your own effort."
It's obvious that this isn't real Rare Candy. This is on sale at numerous Pokémon shops around Japan. What's so rare about that? Come on.