Tsukino's little sister.

Since Tsukino is a "love child", Mizuno has the support of her father. They have a bit of a rivalry over Azuma, whether for his baking skills or his heart. She is quite competitive, and not very honorable.

~!Once, Azuma told her that if he won against her in the newcomer's competition, then she had to call Tsukino onee-san, as a younger sister should. In exchange, if he lost, he would have to work at her store. Mizuno lost, but at first refused to call Tsukino onee-san. She later consented to it, but also came up with another gamble: if Azuma lost against "Koala-chan," or Mokoyama, then Tsukino would have to give up her rights to owning Pantasia, complete with contract. Azuma and Mokoyama tied, but Mokoyama gave up, making Azuma the winner. As of what happened to the ownership of Pantasia, Mizuno is still going for it.!~

Kazuma Azuma wants to make bread. Not just any kind of bread, though. He wants to make a bread that represents Japan itself and can stand toe-to-toe with rice as a national food. Thanks to his legendary "Hands of the Sun," unnaturally warm hands that allow dough to ferment faster, Kazuma's bread is like a slice of Heaven. 
 
And when the Pantasia Rookie Competition arrives, everyone will get a taste of his skill! Along with his friend Kawachi (who's only in it for the dough), he’ll go up against koala karate masters, Harvard bread scientists, samurai with rolling-pin swords, and more! Can Kazuma create bread like naan other and bake his way to glory, or should he quit before he's toast? 
 
(Source: Right Stuf)

Azuma Kazuma isn't terribly clever, but he's got a good heart and great skill - at baking. Since childhood, he's been on a quest to create the perfect bread to represent Japan internationally. Now, he seeks to enter the famous bakery Pantasia, in hopes of reaching his goal. But plots abound... 
(Source: Anime News Network)

Mizuno Azusagawa