{video} Her hands move in a blur. Then they stop, frozen like stone. Sakura Kokumai is 27 years old and could be America’s best hope for a medal in karate at the Summer Olympics in Tokyo. She has a menacing presence in the dojo, even though she is not quite five feet tall. Somehow, when she puts on her “gi,” or uniform, Kokumai seems to grow. “Whenever I wear a gi, I feel very strong. I feel confident, and I feel more like myself,” she says. There are two types of karate debuting at the Tokyo Games. One is sparring, called kumite. The other is a series of precise movements done individually, called kata. “I always exp (full story)