"Sometimes I cry, but only when I'm at home on my own," says Tetsuya Sakurai, one of a select few who has paid $6,000 for an intensive -- and stressful -- training course to become a sushi chef in Tokyo. To the untutored, a little ball of rice with a slice of raw fish on top may look like a simple affair. But students on the twice-yearly course in the Japanese capital soon learn that for masters of the art, there is so much more to it than meets the eye.