Shiba was a Chūnin from Kusagakure. He and Midori were the personal guards of the Grass Daimyō during the Chūnin Exams. They were assigned to make sure Gaara lost to Sasuke Uchiha, making their daimyō win a bet with another daimyō. Gaara was quite mad and killed them both, which saved Naruto and Shikamaru from the same gruesome fate. (Source: Narutopedia)